Firefox locks up then fades away. This just started a few day's ago and seems to happen when I am playing Lexolous in Facebook.

Question

I tried uninstalling firefox and reinstalling, but the problem continues. I also ran AVG to check for worms or viruses to no avail.

Answer 1

It's a little complicated because Firefox plays some video formats itself without a plugin. For others it may use Flash, the Windows Media Player, QuickTime, or another plugin depending on what the page specifies and what plugins you have installed.
Also, some sites use a script to start the video after the page loads. Facebook is now doing this as you scroll down, playing when a video comes into view and pausing when it goes out of view. Fun, hunh?
Because of this, there's no universal solution for clamping down on all videos.
Here are a couple of built-in settings that might help:
(1) For videos Firefox plays itself in the built-in HTML5 video player, there is a preference you can change: media.autoplay.enabled (but scripts in the page can bypass that)
(2) For plugins, you can set "Ask to Activate" on the ones you do not want to run automatically. Visit the Add-ons page using either:
* Ctrl+Shift+a
* orange Firefox button (or Tools menu) > Add-ons
In the left column, click Plugins.
When you visit a site that wants to use the plugin, you should see a notification icon in the address bar and one of the following: a link in a black rectangle in the page or an infobar sliding down between the toolbar area and the page.
Beyond that, you would need to find one or more add-ons.