flash crashes
The latest version of Adobe Flash/Shockwave has ruined my Firefox experience. Websites do not load and videos do not have sound. I have uninstalled, downgraded, upgraded and done every "solution" Firefox has provided. Just like many people in forums, nothing works. Please fix this problem.
Wšykne wótegrona (2)
This is some standard guidance that addresses the most common issues. I'm sure you've seen some of it before, but just in case:
(1) Make sure all recorders/downloaders that interact with Flash media are as up-to-date as possible, or disable them.
(2) Disable hardware graphics acceleration in Firefox and in Flash
(A) In Firefox, un-check the box here and restart:
orange Firefox button (or Tools menu) > Options > Advanced > General > "Use hardware acceleration when available"
(B) In Flash, see this support article from Adobe: http://helpx.adobe.com/flash-player/kb/video-playback-issues.html#main_Solve_video_playback_issues
(3) Disable protected mode (Windows Vista/7/8)
See this support article from Adobe under the heading "Last Resort": Adobe Forums: How do I troubleshoot Flash Player's protected mode for Firefox?
For about another month, Adobe is still supporting Flash 10.3. This may not work as well as Flash 11.x on some sites, but probably can play videos and handle the other basics. http://www.adobe.com/special/products/flashplayer/fp_distribution3.html (scroll down for 10.3).