Ken,
I don't really know the technical side of this stuff but..
I have up-loaded to You Tube and FB. I use what ever the camera records it in. .MOV or MP4. My little Sony cam has HD MP4 capability.
I let the host site determine what to do with them.
http://www.google.com/support/youtube/bin/answer.py?answer=55744
Here's my humble video offerings...
http://www.youtube.com/user/Ztex?feature=mhum