The most recent version of Firefox Nightly Edition (Firefox 46) has introduced a feature that will automatically replace older YouTube embed codes that use Flash, with their HTML5 counterpart, as gHacks reports.
In the beginning, as Flash was the dominant force in terms of media streaming on the Web, YouTube offered users the option to embed its player on third-party sites using HTML object tags, just like many other Web video streaming services at that time.
As the Web continued to develop, simpler embedding systems powered by the HTML iframe tag appeared, capable of working with the newer HTML5 video technology.
This new method of embedding videos became the norm, even for YouTube, and the old object system for Flash videos fell to the side.
As HTML5 becomes the standard for YouTube, Mozilla has not forgotten that millions of YouTube videos are still embedded on the Web with the old object-based embed code.
As the browser maker is anticipating that Flash will become obsolete at one point or another, it is also expecting that this will also break the millions of videos embedded via the object method, which require users to have Flash installed to work.
To address this issue, Mozilla has included a small workaround in its browser's source code that will automatically rewrite Flash object embed codes for YouTube videos into its iframe version.
This feature has been added to Firefox 46, is turned off by default, and users can turn it on themselves by going to the about:config section and enabling the option "plugins.rewrite_youtube_embeds" (see the image below).
For now, Mozilla has done this only for YouTube, and not for Vimeo, DailyMotion, or any other video streaming service that used/uses Flash to stream videos.