I've found myspace to be very flaky. YouTube has been much more reliable. Although there are some issues with video/audio synch on YouTube, generally if you hit the pause button and let YouTube get ahead of itself on the stream it works fine. Myspace seem to fail very frequently.
I'll keep both sites running for the forseeable future, although I'm not ready to add yet another "networking" site to our portfolio (facebook, acousticfriends, secondlife, mynavelcontemplating.com ........ actually I made that last one up).