Hi chandrakant, sorry to hear that you are facing this problem. Does this happen with all videos or only on specific websites? Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance). Do not click the Reset button on the Safe mode start window or otherwise make changes. [https://support.mozilla.org/kb/Safe+Mode https://support.mozilla.org/kb/Safe+Mode] [https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes] Also make sure that your security software (firewall, anti-virus) isn't blocking the videos. If it doesn't solved your problem, feel free to ask in Reply Section. Thanks for raising your question in Mozilla Support Forum.

Whoops, it looks like your question duplicated. You can find additional replies here: https://support.mozilla.org/questions/1287469