playback of downloaded movies
 

When I try to playback downloaded movies I get a message that Quicktime is missing some plugins and I should go to the Quicktime site. It does not spell out what to download so I'm stuck without a solution as to what software to use.

Are you using OSX or OS8/9? Might I recommend you get VLC which has built in codecs to play almost all video types. http://www.videolan.org/vlc/ (choose nearest mirror site) To see what it can play see http://www.videolan.org/vlc/features.html
I use it for some video playbacks & QuickTime for others by setting the defaults for those types of video files. VLC is much better & reliable for previewing however.

What plug-ins should you get for QT? Not sure about what apple suggests. I'd suggest DivX, - XviD, - 3ivx, oh & divx doctor. I do know one of the ones apple suggests is very good for encoding.