I think everyone on the planet has seen this already but just for completeness:
can do!
best Volare! ever
Stayin’ Alive In The Wall (best mashup ever)
Squirrels In My Pants
Satisfaction (not a Stones cover)
Viking Kittens
Dark Tranquility - Terminus (Where Death Is Most Alive)
I better stop and let other people have a chance to post some of what I’ve kept bookmarked for years. 
I’ve killed at least one video thread with this link in the past, but still…
Judge Dread - Big Six
Warning: completely NSFW
This is the descriptive part of the post, giving an indication of the linked video:
Behold, a Bollywood Terminator/Matrix knock-off, which is equal parts WTF and WIN:
This is a link to the video.. Go ahead, click it.
What.
The.
Fuck.
Except for the fact that that seemed to be ripped from the “director’s commentary” part of the DVD, all I could think was “if I was 9 years old and watching this, it would be the coolest movie ever”.
Can’t watch any of the videos here, so I’m not sure if someone else already posted this, but the Clown Quartet always sends shivers down my spine.
I have watched some of these videos
::thousand yard stare::
I am thinking maybe I should not have.
Bee Gees vs Pink Floyd, fine. Man-bike, not so much.
Here’s something a bit less disturbing (a bit).
I am now afraid of god.
Would it kill y’all to freaking title these?
These are a portion of edarem’s ouvre. Edarem was a children’s television host years ago who got in trouble for having a bit too special a relationship with some of the kids. He went on to make some YouTube videos that are creepy when shorn of context and retch-inducing when contexualized. As his jurisdiction did not allow sex offenders to go online, he was serving a prison sentence last I heard.
Apache!
This is all kinds of cool. Seriously. When is this coming to cable?
Sebastian Cabot does Dylan.
I’ve got a whole album of this stuff.
Enthiran. It’s the highest grossing film in Indian history.
The Onion AV Club recently did an article on it for their “I watched this on purpose” series.
Cows.