This predates YouTube, but it’s ON YouTube, so… (NSFW):
I have two favorites. Hope this isn’t cheating:
Fan-made extended Gears of War trailer.
And of course, Happy Mornings.
The Evolution of Dance
And for a little holiday spirit== Hey Ya Charlie Brown Style
Pollak is great! If Walken runs for President again, Pollak should be his press secretary. No telling him from the real thing.
Wow, thank you for this, I’ve never heard this guy before but will definitely check out his stuff 
It’s a Big Ad.
Current Favorite…Some one had way too much time on thier hands.
When McDonald’s had Nintendo-licensed toys in their Happy Meals a couple months ago, they used an ad very similar to this sketch. It made me wonder if the same people who did this sketch helped with the ad, or if it was just a plain rip-off (the sincerest form of flattery). I love the fact that this particular print of the video has an “ebaumsworld.com” watermark on it- in other words, it was stolen from a thief. How ironic.
While we’re on the subject of Mario, there’s the Nintendo Amusement Park, which is experimenting in New York City. (The reason the ad is in Japanese is because the people want to make a deal with Disney and Nintendo to install the ride in Tokyo Disneyland.)
That reminds me of this one where one guy is playing the Mario Bros. theme on 2 guitars simultaneously. Pretty darn amazing if you ask me.
Here’s one I just found today that ranks pretty high on the unintentional humor scale. It’s some douche from Bank of America singing U2’s One, but he’s changed the lyrics so it’s now about a merger they made.
This is the most awesome clip I’ve found, guy on Best Buy security camera:
And this is hilarious too, even though it’s in another language:
Wow. I haven’t bothered to come into this thread because I just knew the video I wanted to mention would already have been posted several times. But no, oddly, so here:
Psst, see Post #64.
The true story of Charley the Unicorn.
Lucy Daughter Of The Devil (Mature NSFW, possibly tasteless, but oh so good)
The last one is a fake though, isnt it?
Aicha must be in love after seeing this.
She moves how?!
My brother sent me this:
It took 15 years to build this WORKING scale model of a Ferrari 312pb. Tiny yowling flat-12 engine and all.