Little tips for better Slackware desktop experience. Most of these can be used in other Linux distributions as well.

Double-clicking in file manager (Thunar) shows no video (audio is ok, so program is running). Running mplayer from command line is fine. Turns out gui version is gmplayer - running from console shows this error message

Failed to open VDPAU backend libvdpau_va_gl.so

So, just edit ~/.mplayer/gui.conf, find the line for vo_driver and set it to gl. Show be ok after that… at least in my case it is.