This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

Video frames do not scale properly

more options

In Firefox video frames don't scale properly. This affects both HTML5 videos e.g. youtube.com and Flash videos e.g. twitch.tv. When switching to Cinema view in youtube, or closing the side panels in twitch, the frame will extend to the left and right, leaving black bars at the side, but the video does not scale and the frame does not increase in height. I don't have the issue in Safe Mode and also not in Chrome. However I still have the issue in Firefox with all extensions disabled. I tried to delete cookies, cache and refresh Firefox, but the issue still exists. I also tried to disable Hardware acceleration in both the Flash Player and Firefox, but that also does not solve the issue.

In Firefox video frames don't scale properly. This affects both HTML5 videos e.g. youtube.com and Flash videos e.g. twitch.tv. When switching to Cinema view in youtube, or closing the side panels in twitch, the frame will extend to the left and right, leaving black bars at the side, but the video does not scale and the frame does not increase in height. I don't have the issue in Safe Mode and also not in Chrome. However I still have the issue in Firefox with all extensions disabled. I tried to delete cookies, cache and refresh Firefox, but the issue still exists. I also tried to disable Hardware acceleration in both the Flash Player and Firefox, but that also does not solve the issue.

Chosen solution

Safe Mode also deactivates userChrome.css and userContent.css. If you have created either of those files to customize Firefox, you might check whether those rules affect video sites.

Oh, hold on, the problem continues even after you used the Refresh feature? That would have removed those customizations. (I'm assuming you tested before reverting to older settings.)

Read this answer in context 👍 1

All Replies (2)

more options

check this:

  • see if there are updates for your graphics drive drivers

https://support.mozilla.org/kb/upgrade-graphics-drivers-use-hardware-acceleration

  • disable protected mode in the Flash plugin (Flash 11.3+ on Windows Vista and later)

https://forums.adobe.com/message/4468493#TemporaryWorkaround

  • disable hardware acceleration in the Flash plugin

https://forums.adobe.com/thread/891337 See also:

more options

Chosen Solution

Safe Mode also deactivates userChrome.css and userContent.css. If you have created either of those files to customize Firefox, you might check whether those rules affect video sites.

Oh, hold on, the problem continues even after you used the Refresh feature? That would have removed those customizations. (I'm assuming you tested before reverting to older settings.)