i have the same problem. i have tried at least 50 videos and none of then work. I have only had this problem for the last couple weeks when i first go the phone they worked then just all of the sudden nothing works.
I've tried several other videos on youtube i even connected to wifi and i still cant play any youtube videos is there a setting that i need to change? Could this be a defect in my phone?
Which app are you using to play the Youtube videos?
Its the You Tube Videos app thats on my Eris that was already loaded on my phone.
I'm on the fence on what to do, my 30 day return time frame will be approaching in mid January and if these issues aren't fixed in the next software update im stuck for 2 years with a phone that is buggy.