I got .pls, .m3u, and .mp4 t open with KMPlayer. I'm still trying to get .avi and .flv to open with KMPlayer.

newbie tips:
- using emelfm2 to edit the text files makes it all easier (I did it as root)
- I never delete lines, just comment out the line with a # symbol at the beginning of the line (#video/mpeg etc...)
- reboot for it all to take effect. I thought I messed up because nothing worked until I rebooted.
- there may be a slight lag so as pipline said, click your file only once

Hope that helps some people. Thanks goes to pipeline for making my N800 better.