If I try to play a movie from terminal by using mplayer, this is what I get:

/home/user/MyDocs/.videos/Footrot Flats (1987) # mplayer Footrot_Flats.avi
MPlayer SVN-r30099-4.2.1 (C) 2000-2009 MPlayer Team


MPlayer interrupted by signal 11 in module: unknown
- MPlayer crashed by bad usage of CPU/FPU/RAM.
Recompile MPlayer with --enable-debug and make a 'gdb' backtrace and
disassembly. Details in DOCS/HTML/en/bugreports_what.html#bugreports_crash.
- MPlayer crashed. This shouldn't happen.
It can be a bug in the MPlayer code _or_ in your drivers _or_ in your
gcc version. If you think it's MPlayer's fault, please read
DOCS/HTML/en/bugreports.html and follow the instructions there. We can't and
won't help unless you provide this information when reporting a possible bug.
/home/user/MyDocs/.videos/Footrot Flats (1987) #

The default players lagginess seems to differ. If I restart the player the lagginess may be worse or gone. It's weird.

All my videos are in the device's own memory.

The kmplayer seems to work fine after a quick test, so I'll try to use that in the future. Thanks for all of your help! =)