I tested 400x480 resolution on mplayer a few days ago. Works flawlessly at 7 fps, which is great. It's not fast enough for serious video playback, but it's brilliant for tutorial videos and slideshow videos (e.g. created in iphoto). I added that as a new resolution for media converter. Download here:
https://garage.maemo.org/frs/?group_id=26

Has there been any development on getting mplayer opera plugin that would be able to open flash videos on mplayer?