YouTube user TehN1ppe has figured out a way to get YouTube to host 10-hour videos. Apparently he's "a 17 year old boy from FInland [sic]," according to his YouTube profile. The long-video thing is actually not a big secret -- you just have to abide by YouTube's guidelines (no copyright infringement, etc. etc.), then eventually you'll be granted long-upload privileges; those who don't abide by the rules are limited to 15 minutes. Read more on that here. Anyway, this kid decided to shoot for TEN HOURS and managed to get a lot of videos posted before YouTube disabled his ability to add more. Here are some good ones. Yes, they're rather repetitive. See you in 50 hours, people!
Epic Sax Guy
Apparently a 1080p version is coming, though it may take "ages" for YouTube to process the massive source file. Given that this video was uploaded roughly a month ago, I'd say "ages" is about right.
Trololo (Eduard Khil)
The magic almost literally never ends. I can promise you that your mind will melt before you hit the ten-hour mark. (Please don't try. Please.)
Watch out for that snake!
Taking the Hobbits to Isengard
Based on this video, this rides the line between annoying and kind of catchy.
"Hypnotoad also has its own television show called 'Everybody Loves Hypnotoad'. It consists of a stationary camera filming the Hypnotoad and its noise continuously. Despite the odd premise behind the show, it ran successfully for over three seasons, possibly because it hypnotises the audience." - Futurama Wiki.
You've certainly played ten hours of Tetris before, so this should be no problem.
More, if You Dare
Check out TehN1ppe's channel for tons more. He has almost 11 million views. I guess this proves that a YouTube video doesn't need to be viewed through the end in order to rack up a "view." Also note that this guy apparently can no longer upload videos longer than 15 minutes due to "stupid FOX" (presumably a copyright claim related to Hypnotoad?), so he may have to find another channel for his ten-hour masterpieces.
Disclaimer: these videos are posted for entertainment and brain-melting purposes only. And by "entertainment" I mean "pain"; also you may be hypnotized by the Hypnotoad and made to watch more videos. Um. Enjoy!