By recommendation from Jay Dedman I moved from Youtube to blip.tv to host my videos (almost forgot I started with castpost). I thought blip had roughly the same features as youtube, but I liked the fact that when you embed videos, you don't have a large triangle and YOUTUBE on your video. Just looks better with blip.tv.
But yesterday I discovered an important reason why blip.tv is better for use in a development context. Namely, it is very hard to download videos from youtube! It's quite easy from blip.tv. This feature is helpful if you want to put the video on a server or on a CDrom to play it back to an audience with unreliable or low bandwidth connectivity. Though it is not impossible on youtube, it is not as easy as on blip.tv