Hint: Some drivers - e.g. vidix - require sudo, if permission issues are shown.
Greetings tinypoodle!
Sudo makes no sense for a GUI like GMplayer, unless it can be imbedded in a 'conf' file, that GMplayer seeks, inorder to launch.
All my references apply to mplayer - personally I have not touched gmplayer ever since TC came into life...
Doubtful if gmplayer could change user executing mplayer, you might have to start gmplayer as root if you want to make use of vo drivers requiring root permission.
Where exactly does GUI GMplayer 'conf' file actually reside, in TCP 4.7.3? The linux file structure is completely new to me, especially TCP.
You might want to consider using a good file manager (e.g. rox-filer, mc, emelfm).
Finally, your dialog "if permission issues are shown" need's further explanation, to newbies . . .
When you start mplayer from a terminal, mplayer will show a lot of output which helps with troubleshooting, amongst other lacking permissions for vo drivers, e.g:
tc@box:~$ mplayer -vo xvidix test.mpeg
[...]
No vidix driver name provided, probing available ones (-v option for details)!
[cyberblade] Error occurred during pci scan: Operation not permitted
[mach64] Error occurred during pci scan: Operation not permitted
[mga] Error occurred during pci scan: Operation not permitted
[mga] Error occurred during pci scan: Operation not permitted
[nvidia_vid] Error occurred during pci scan: Operation not permitted
[pm3] Error occurred during pci scan: Operation not permitted
[radeon] Error occurred during pci scan: Operation not permitted
[rage128] Error occurred during pci scan: Operation not permitted
[s3_vid] Error occurred during pci scan: Operation not permitted
[SiS] Error occurred during pci scan: Operation not permitted
[unichrome] Error occurred during pci scan: Operation not permitted
[VO_SUB_VIDIX] Couldn't find working VIDIX driver.
Error opening/initializing the selected video_out (-vo) device.
[...]
Video: no video
versus
tc@box:~$ sudo mplayer -vo xvidix test.mpeg
[...]
No vidix driver name provided, probing available ones (-v option for details)!
[radeon] Found chip: Radeon Mobility M6 LY
[radeon] Video memory = 16Mb
[radeon] Set write-combining type of video memory
[radeon] DVI port has LCD monitor connected
[radeon] CRT port has no monitor connected
[...]
VO: [xvidix] 640x480 => 640x480 Planar YV12