@
kurochan: Unfortunately you do not give any information about your PC and/or about the type of movie you're trying to play. However, for the time being, please don't bother about "Force RGB". As the message you're getting is "unknown file format", you probably need to install some codecs. Have a look at
this post.
P.S.: Two tips
- Preferably stay away from codec-packs and if you nevertheless find you should use them: certainly do not install each and everything contained in it, but instead be very selective!! (The more you install the harder it is to find out and get rid of the source of possible conflicts and errors)
- To find out what type of codec you need, have a look at the second item of my post "Help to Help" (there's a link to that post at the bottom of all my messages!)