Really nice application!
There only a few things to optimise:

1. The seek bar has sometimes a bug which makes it useless because the bar freezes while something is playing and every time you want to use it the song or video starts at the beginning

2. It is not possible to search with the keyboard like it is possible in Nokias MediaPlayer

3. If I play a song in folder view the song stops and the no other song starts after that. I would expect (like symfonie) that the next song in that folder will be played which would be nice