Usability 
The popular video sharing site Vimeo is dedicated to true user generated content and doesn't allow commercial videos.
There's a lot of interesting content on Vimeo but it's hard to access from any phone except an iPhone or Android device. There's a bug in the site's browser detection logic that redirects Symbian, bada, Opera Mobile, BlackBerry, Windows Mobile and other mobile browsers to Vimeo's desktop site even if the user explicitly enters the mobile url!
The videos on the desktop site are Flash and don't work on most mobile devices. The ones on the iPhone/Android Vimeo site are MPEG-4 packaged, H.264, AAC encoded and should work on most modern handsets - if only there were a way to get to them