UPDATE (Sep 27, 2009) : There are various Streaming Video apps on App Store (firmware v2.x and up). Some of my favorite Free Video apps on iPhone available on App Store are : (search these names on the App Store)

Joost
Truveo
VSnax

MxTube app available on Cydia will even let you watch high quality videos on iPhone. It also lets you download and save them to your iPhone!
So, you are not so happy with videos on Youtube(!!) and you want to search for videos from different video sites – say DailyMotion.com and so …