Hi   !
When you say:   "Flash doesn't work",   are you talking about
Shockwave Flash   ?
If so,   do you have it set to   'always activate'   ?

If,  however,   you are talking about   'Flash Player':
Go to   Control Panel > Programs > click on  'Flash'  (if it's there);
the  Flash Player Settings Manager  shoud appear and you can check to see if it's updated en activated.

All flash content - youtube, embedded in news stories etc. just shows an "f" in a circle and doesn't play. Has always worked. Only thing that changed was firefox update to 49.0.1.

I think f in a circle indicates you have an add-on like Flash Block or Flash Control that requires you to individually activate Flash players. Also, YouTube should use the HTML5 player by default, so you might also have a YouTube-specific add-on that modifies how it plays videos.

You can view, disable, and often remove unwanted, unknown, or just plain broken extensions on the Add-ons page. Either:

• Ctrl+Shift+a (Mac: Command+Shift+a)
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Extensions. Then cast a critical eye over the list on the right side. All extensions are optional. If in doubt, disable.

Often a link will appear above at least one disabled extension to restart Firefox. You can complete your work on the tab and click one of the links as the last step.

Any improvement?

In case it's relevant:

There are three possible default permissions for Flash, which you can set on the Add-ons page. Either:

• Ctrl+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Plugins. Then check the list on the right side for Shockwave Flash and you can adjust the permission level:

• Ask to Activate - sites need individual permission to use this plugin
• Always Activate - sites can use this plugin without individual permission
• Never Activate - plugin disabled

With Ask to Activate, when you visit a site that wants to use a plugin, you should see a notification icon in the address bar and usually (but not always) 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.

The plugin notification icon in the address bar typically looks like a small, dark gray Lego block. When the page wants to use a blocked plugin, the icon turns red to alert you to the concern.

If you see a good reason for the site to use the plugin, and the site looks trustworthy, you can go ahead and click the notification icon in the address bar to allow it. You can trust the site for the time being or permanently.

But some pages use plugins (especially Flash) only for tracking or playing ads, so if you don't see an immediate need for it, feel free to ignore the notification! It will just sit there in case you want to use it later.

Hi   again  !

First:   see if there are updates for your graphics drivers:
http://mzl.la/1xKsEca
Would you take a look at:
https://support.mozilla.org/en-US/kb/fix-common-audio-and-video-issues
Also see:   'Flash Plugin - Keep it up to date and troubleshoot problems':     http://mzl.la/1BAQTH9
If nothing else works,   maybe an add-on will do the trick:
https://addons.mozilla.org/en-US/firefox/youtube-flash-video-player/

Good luck and keep us posted   !