Debian 5 (Lenny) 2.6.26-2-686

When logged in as my main account I can play videos in Totem and VLC. But when logged in with my "mythtv" user account, all I get is a blank screen, but the audio works.

I suspected a permissions issue and thought maybe I should add mythtv to the video group? Something to try. But when I go to System > Administration > Users and Groups, I don't have a mythtv user listed. The user does exist, I log in with it. Also, I have:
mythtv:x:113:121::/var/lib/mythtv:/bin/sh in /etc/passwd

I just don't know where to begin looking for this, since it is working for other users, just not the one I need it to.

Thanks for your help.

I think Users and Groups only show from UID 1000 and above (considered "human" users). I suggest you compare the group membership for both users (you can run groups command and see the membership). Maybe mythtv is missing membership to audio (or something like that).

Thanks for the reply. I ran the "groups" command, and mythtv is:
mythtv dialout cdrom audio video
my regular user is:
xxxxx dialout cdrom floppy audio src video plugdev netdev powerdev

I changed to root and did:
# usermod -G dialout,cdrom,audio,video,plugdev mythtv
# groups mythtv
mythtv dialout cdrom audio video plugdev

but when I log in as mythtv, I still only have:
mythtv dialout cdrom audio videos

I didn't get any errors, though.