I've found that the N900 plays most every video codecs. Please see the attached screenshot for the settings in Format Factory for the N900 in case you have problem with the video. (att. 1)

The N900 occasionaly has problem with the audio (ie AC52), so in that case just use FF to convert the audio to mp3 and leave the video unchanged (it's called "Copy" in FF). (att. 2)

Hope this helps some users.