I just reviewed this document, Video Module FAQ, and I suspect this passage has not been updated in a while since it refers to 4.5 version of Jive.
H.264 @ 500kbps, audio quality 64.0 kpbs. The player is sized at 400x333 for pre-4.5 and 500x328 for 4.5 and the video has a resolution width of 768.
I am recording new videos, and have yet to be able to figure out the best height and width to fill the screen and get the best resolution. Can someone at Jive please comment?