Check if the solutions given in this article help: Uninstalling add-ons. If your problem is still not solved, see the Troubleshooting section at the end of that article for further help.

I tried everything that dynamite linked to, but it will always keep reinstalling itself. There must be some way of getting rid of this? This is fraudulent by Divx

Manually delete DivX folder in /Library/Application Support Manually delete Divx related components in /Library/Application Support/Mozilla/Extensions (not sure if second is necessary).

Fifth question on this page: http://support.divx.com/faq/view/supportFAQen170/DivX-Plus-Web-Player-210-Frequently-Asked-Questions

Q: Can I uninstall DivX HiQ?

A: Yes, but DivX HiQ is part of the DivX Plus Web Player. They can be removed together through “Add/Remove Programs” on Windows, and using “Uninstall DivX for Mac” in the DivX applications folder on Mac OS X.

Yes!!! Yihaa! I deleted DivX folder in /Library/Application Support/Mozilla/Extensions and Divx HiQ and Divx plus web player disappeared in the add-ons manager.

P.S. Uninstalling of the divx bundle didn't work for me.

Yes!!! @pavelbonev It worked for me too!!!

where is /library ? i can't follow the steps as i don't know where this folder is! please help! uninstalling doesn't work - i just get 'programme not responding'

“/Library” means the Library folder on the root level of the system, the one you see when you double-click your hard disk icon. If you don’t see a hard disk icon, switch to the Finder and just choose “Computer” from the “Go” menu.