The official limit is 95MB. At least that is what i put in the configuration as the most memory allowed for a single thread.
If you keep the movie under 80mb, you should be more than fine. Also be aware, i believe there is a maximum time of 600 or 1200 seconds (i can't remember right now, i'm at work) to upload a video. If you are on a slow connection, or it takes longer to upload, it may fail.
No pixel limit, it will automagically format the video to 4x3 or 16x9 (yeehaw).
Nick, if you are continuing to have problems send me an email, firstname.lastname@example.org
, and i'll look into the issue.
Hopefully you guys enjoy the newly redesigned site.