WMV and Flash are resource hogs, but the tests kind of bring down to earth all of the "The N900 plays everything I threw at it" talk. "Everything" is a relative term, but it still blows away the competition of only MP4 or WMV.
As long as it plays divx, xvid, MP4, wmv (perhaps mkv) and mpeg in standard def I will be happy . Only so much to notice with a 3.5" display anyways.

No to mention software improvements down the road