Hi, that is Adobe Flash Player, which is installed on your computer and not Firefox, so you would have to uninstall it from your programs. However if you do that, any Flash videos will not run. You can if you wish, set it to Ask to Activate or Never Activate, instead of Always Activate in the Add-ons Manager > Plugins.

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I am sorry. I do not know what/which is a 'flash player'. Does this mean youtube video or short videos posted on f.book would not run? I am trying to figure out why I am getting the apple spinning ball of pause and read to look at biggest hog on activity monitor.... but am quite ignorant re computers and hesitant to mess things up in trying to fix things. THANK YOU for patience and help.

Flash player is software developed by Adobe that many websites use for videos, games, and other items. Flash player can cause slowness, causes many crashes, and often has security issues, but enough websites use it that its not really possible to avoid it. Youtube, for example, has switched to a new technology for playing videos that doesn't need flash player, but facebook still uses flash player for many features. So, yes, you should probably keep it.

If you want, you can choose which websites to allow flash player to run on on a per-website basis. Go to "about:addons" in the address bar, click on the "plugins" tab, and look for something called "shockwave flash" or similar. In the dropdown menu next to this, you can choose "ask to activate". This way, firefox will ask you before running flash on websites, so you can only use flash when you want to.