Android Media Player Library

Vitamio looks pretty good, wmv and flv are on their support format list, though I've never used it myself.

Media formats
Many audio and video codecs are packed into Vitamio beside the default media format built in Android platform, some of them are listed below.

divx/xvid
wmv
flv
ts
rmvb
mkv
mov
m4v
avi
mp4
3gp