divx

i have a 2011 macpro and for some reason my mac wont play the "how tovideos" in the how to section of the help section. i downloaded divx player twice. help please

Which videos are you referring to? It's very possible that they are in fact not DivX videos.

Perian might work for that

Perian - The swiss-army knife of QuickTime® components

I think what the OP is *trying* to say is that BECAUSE he downloaded a DIVX player, NOW the videos included in the "how to" section of the help files won't play properly. I've heard many reports of some DIVX players messing up Quicktime operations, but all I can suggest is uninstalling the DIVX players and see if that fixes the issue.