Mozilla has added a feature to Firefox 46 that will convert old YouTube Flash code to HTML5 Video automatically. The Flash code works fine after all these years, but only if Adobe Flash is installed in the browser. If that is not the case, a “plugin is missing” error message is displayed.
It needs to be noted that Firefox won’t enforce the use of HTML5. If Flash is installed in the browser, nothing changes at all as Flash will be used in the case to power the video player. Mozilla plans to launch the feature in Firefox 46. It is already part of the organization’s Nightly web browser and enabled by default.
Firefox users who don’t require the feature, can deactivate it in the following way:
- Load about:config in the browser’s address bar.
- Confirm that you will be careful if a warning prompt is displayed.
- Find plugins.rewrite_youtube_embeds using search.
- Double-click on the preference name.
If you set it to false, Firefox will not rewrite old Flash YouTube embed code if Flash is not installed or enabled.