There is a lot of bad things going on about flash and java be it in performance and or in security. Being aware of those you’d disable them but it does hamper your browsing experience. HTML5 might be working on YouTube to replace flash but there are ton of other sites that use flash to show videos or stream live TV (like the Olympics on CBC.ca). So either you’re not watching it or you’d be installing them back again. But the newer version of Firefox has a feature that lets you choose where to enable those plugins and extension while non existent to other sites.
This is very simple to do and will save you some trouble of fearing those security problems from malicious sites. Although this doesn’t mean that you’re totally safe but allowing these plugins to run on well reputed sites is much safer than letting them run on every site. There are two ways to currently do this:
The first one is going through the plugin list on your Firefox, then select how should your plugins act on default. Either they should be “Deactivated”, “Ask to run” or “Run automatically”. You almost don’t want plugins to run automatically everywhere. So you’ll have to choose “Ask to activate” on plugins like Flash and Java. I mostly do it on all of the plugins though as Firefox will prompt for a approval if the site contains content that the plugin needs to operate.
Doing this, Firefox will prompt you every time there is some content on sites that need those plugins to run. Then you must choose to allow it once or for Firefox to remember your choice and let it run every time on your site. If you trust the site you can choose to “Allow and Remember” if not and you just have to use the site once, allow it to run once.
The other way of doing is to manually allowing plugins to run on sites after visiting it. After visiting a site, you’ll see a globe icon on the navigation bar, you can click the globe that will show more information about the site and the permission allowed to the site. Here you can edit the permissions for the plugins to run as well.
After you click on “More Information”, you are provided with the following option where you can customize the plugin permission for the site. Choose the plugins that you need to run and disable the ones that you don’t need.
That’s it, You’ve customized your Firefox to allow plugins only on specific sites while disabling them completely on the others. This might be the safest way to use these plugins because we don’t yet have other options to replace them.