following this thread:
http://talk.maemo.org/showthread.php?t=32935
the user made startup videos for the N900 that run perfectly.

Using the Gspot app for windows it says:
Video
codec = xvid (H.264 or MPEG-4)
resolution = 800x480
Bitrate = 1447kb/s
FPS = 25
Qf (i dont know what that is) = 0.151 bits/pixel

Audio
Mpeg-1 Layer 3 (MP3)
Bitrate = 128kb/s @ 48KHz

Hope this helps

Edit: the stats for the preloaded video trailer "9" is:
Video
codec: MPEG4
resolution 800x480
FPS23.98fps
Audio:
AAC 44100Hz stereo 1411Kbps

Unfortunately i cant see what the Video bitrate is