Why can't I get Divx to work?

[PreacherwithPriors]

I usually use RealPlayer in all my video downloads. It is very easy, and when the curser is on the video the little box pops up to download in Realplayer, etc, easy. But many videos are already controlled by Divx, and Realplayer won't work. But I have installed Divx several times, but cannot download anything. Whenever a video says download in Divx, all I end up doing is downloading Divx again and again but never a movie. What am I missing, besides a few screws?