I've built qtmobility master (6661e93) on Windows using the following approach:

1) Downloaded Qt 4.7.0 for MSVC 2008 from qt.nokia.com
2) Installed into c:\qt\4.7.0
3) Configured and built QtMobility
4) Ran "nmake install"
5) Downloaded example video from http://chaos.troll.no/~tavestbo/webkit/mediaelement/bunny/big_buck_bunny_480p_stereo.avi
6) Compiled and ran demos\player
7) Loaded the downloaded video file
8) Started playback

However the video doesn't play and resizing the player window leaves the video area unpainted.

The same video plays well in the windows media player. My c:\qtmobility\plugins\mediaservice\ directory contains dsengine.dll, qtmedia_audioengine.dll and qtmedia_wmp.dll (and their debug variants).