[help] Quicktime not playing..

Alrighty guys. This has been happening on my Mac since day one but I realised the solution is something I can't figure out myself. Quicktime doesn't play anything. I get the pop up saying I need to install some software, which I clicked okay and downloaded pretty much everything on the page, yet Quicktime wont play any type of video file. Usually I would just play it in VLC but since it isn't working it is slowing down my iMovies. The problem happens with some in browser movies and ones in the player. I tried downloading the new Quicktime from the site but nothing. Any help?

The pop-up looks like this by the way:

[EDIT] And on .avi files the video just stays white and sometimes I can hear audio and on some I can't. [/EDIT]

#298920

Have you tried reinstallation?

http://www.apple.com/quicktime/

#299119

It means u dont have a codec.

#299149

@nbn: Yes.

@ Hobbes: I downloaded everything on the page? What else is there?

#299569

We all know I hate to bump...but this is really bothering me and iNeed () for a iMovie I am working on.

Any help?

#320832