I’m an American and understand it, but I don’t generally have a problem with accents.
I’m usually pretty good with accents - my husband’s Australian, I’ve spent a lot of time around people from all over the world. The one time I was completely flummoxed was when we were staying with a friend (who is Scottish and completely understandable to me). He had a visitor from somewhere in Northern England who could have been speaking a different language. I couldn’t understand one single word he said. Everyone was talking to him as if he was actually using real words, but it sounded like complete gibberish to me.
That explains a lot. I had a really hard time understanding him, since he kept doing a really bad NY accent, and I thought the fact that he kept slipping into an Australian accent was just a side effect of him trying to fake a NY accent. Figures he’s actually Australian. Shame they couldn’t afford a dialect coach, but I guess they spent so much on the CGI minor things like plot, good dialog, actors with believable accents, etc., had to go by the wayside. (Can you tell I didn’t like Avatar?)
The Snapper, also starring the lovely Tina Kellegher.
She has a Newfie accent and is picking up a Scottish accent. I found a report from June 2007 and that’s what it sounded like then. Very odd.
Midwestern American here, no problems.
I thought it funny that Eccleston’s Doctor was always getting comments about his Northern accent, is it that odd to hear in London or was it just odd that an alien had a Northern accent? So the rest of Britain has trouble understanding those accents, too? Would that include Yorkshire? I remember James Herriot’s books talking about how much trouble he had understanding the local dialect.
Some friends and I went thru the first 2 seasons of “The Wire” on DVD, and had to turn on the captions in order to fully understand the drug dealers. There was a lot of druggy slang and “negro dialect” that was just too hard for us to understand otherwise.
I’ll second what someone said upthread about Scottish folks. I spent a week in Scotland and 100% of the time could not understand a word that was spoken to me whenever a conversation was initiated. It helped once some context was established-- then I could understand some of what was said. Funny thing is, I was actually there working with some folks at an oil company, and there was one Engineer from Louisiana who was even harder to understand than the Scottish guys because he had such a think Cajun accent.
No problem here, but I’ve spent significant time in the Midlands and Scottish Highlands, so weird English accents generally don’t give me any trouble. It’s the occasional out-of-vocabulary word that can mess me up (although I’m pretty good with those, it still seems there a neverending supply of regionalisms that would take several lifetimes to learn.)
We’ve taken to turning on the subtitles on British shows, even DOCTOR WHO. Used to be, the actors spoke BBC-English, which was comprehensible to our American ears, but now so many speak in various regional accents, we often can’t make out heads nor tails. Nor cheese nor chalk.
I don’t think (going both ways) that the standard accents are so difficult, I think it’s the regional versions. Or some people (including actors) just don’t enunciate. Who can understand Marlon Brando, when he’s mumbling?
In real life, I’ve had more trouble with Australia & New Zealand accents than British ones. With the former two, luckily people use facial expressions and hand gestures.
What do you mean by understand? I have more trouble translating terms fast enough (queue=line, jumper=sweater etc) into American English than comprehending what they’re saying. But then, I sort of like the Arctic Monkeys so I’m a little used to the accent.
As for the OP, of course we have trouble understanding you at times too. It’d be arrogant to believe otherwise. For example, I like Andrew-Lee Potts a lot, but while watching Primeval I’ve had to rewind and replay things both he and Scottish cast member Douglas Henshall are saying (and yes, I realized that Douglas was Scottish, not English, from the first episode). Which is odd because Andrew-Lee is far easier to understand in Alice…but he also does a fairly decent American accent in Return to House on Haunted Hill, so maybe they asked him to tone it down a bit for Alice. And my parents used to watch EastEnders: if I wandered through the room there was a 40% chance I’d have no idea what anyone was saying on screen.
I hope nobody is taking offence to this thread OP. I meant it in good nature of course. 
To be fair it doesn’t happen very often to me. Dawson’s Creek was the particularly significant example of it. And the guy in Avatar was sort of saying it under his breath, or at least under-annunciating it deliberately.
ETA: You mentioned Eastenders. If there is a fictional hell on earth it’s Albert Square. It’s annoyingly and unbeleivably depressing. I think all the characters have clinical depression.
Thank you!
Midwesterner here. I understand the Arctic Monkeys song with no problem. I had some cognitive dissonance with the Scots accent in that movie clip, but that was mostly because I was trying to figure out if the guy just looked like Brad Pitt or was Pitt–and then of course, toward the end, I think he is just speaking gibberish (but I don’t speak Glaswegian–which is what I think he’s speaking. I’m probably totally wrong. I know someone from Edinburgh and he sounds nothing like the Pitt character, so I’m assuming it’s a Glasgow accent in that clip).
I sometimes have to put the volume way UP on British films (Harry Potter sometimes, but usually more period pieces like Pride and Prejudice etc). I think it’s because Brits tend to speak from the back of the throat or mouth. They also (especially upper crust shows like Masterpiece Theater etc) tend not to move their mouths (lips) while forming words, and they speak more quietly than Americans do. Add to that a lack of facial gestures and rapid responses (I think Brits talk faster than we do) and I admit to being at a loss sometimes.
I once sat across from a guy on the Dover train who was taking his little girl back home from some kind of weekend trip. We got to chatting (at that time I had young kids also, but was by myself in UK for a trip) about this little girl (Georgina). I was doing fine until he said, “wuronouhweytocrnwuhl”. I managed to tease out “we’re on our way” but cnrwuhl eluded me. Finally he (with a look of infinite patience that only Brits can do and is so withering to the recipients) said loudly and slowly “CORNWALL”.
Oh. Why dintchasayso? Geez… 
I do fine with most Brit accents (I can’t identify them, except for the Etonian landed gentry one from years of Masterpiece Theater and other stuff), but sometimes I experience a sort of auditory processing disorder. I hear all the sounds and about a second later, they form into words in my head. Very weird.
I find Kiwi and Aussie accents harder. They’re so broad and twangy with their vowels, if I don’t know the context, I can get lost.
Brad Pitt is supposed to be speaking a “Pikey” accent there, which is an Irish Travelers/gypsy accent. How good it is, I don’t know. I’ve heard people say that it sounds like an extreme Newfoundland accent.
Within Edinburgh, you can get some pretty rough accents, too. It ranges from what sounds to me like Scottish-inflected Queen’s English to what you get in Trainspotting (which takes place in Edinburgh) and beyond.
And towards the end, the youtube video creator has dubbed it over with the sound of the newsreader from Bruce Almighty babbling (because Bruce is controlling his voice)
When I first started working as a barback when I lived in Prague after college, my manager was a Scottish guy with Edinburgh brouge so thick you couldn’t cut it with a claymore. He had a temper, so I was a little intimidated by him and afraid to ask him to slow down. He would tell me something like:
“Goan doon toother bow’um ba un gibit uh wee sprey,”
and I’d have to go sound out what he’d said phonetically to the Canadian bartender for translation (“Go on down to the bottom bar and give it a wee spray,” i.e. spray the downstairs bar for flies). Later I warmed up to him and got less afraid of him and would smile and hand him a pen and pad if I couldn’t understand him after several tries, after which he’d slow down and carefully enunciate for me. 
pravnik you reminded me of a bit from ‘Hot Fuzz’
Edit: Found it!
Interesting - Jim and I watch a lot of UK tv shows and movies, and we never need subtitles. We have a lot more trouble with the really thick American accents, frankly.