I purchased a license for Webroot antivirus and this extension came with the license. So far, so good. It is blocking malicious urls. It works.

I tried to uninstall this add-on manually. I followed the steps that Firefox itself suggested. It keeps popping up and reinstalling itself! DO NOT INSTALL IT!!!

Edit:
So, this is how I solved my issue. After I manually uninstalled it, I restarted my computer. It was gone! Solved!

webroot needs to change its invasive policies, persistent reinstallation, extension removal blocking, no good and easy way of uninstalling. even revo pro could not easily remove. it will not let you remove extensions, if you uninstall normally, it reinstalls by way of extension if you reopen any browser. for those purchasing or preloaded 2 months webroot secureanywhere through best buy, you will be constantly reminded 3 weeks before it expires, and it will haunt you and even its own forums suggestions on ways to remove are not working.