&gt; fragment cross-platform compatibility<p>No, it wouldn&#x27;t have, in the long run. H.264 was chosen by the <i>hardware</i> manufacturers (phones, video cameras, etc), and the software world would have fallen in line. As they did.<p>Besides, any temporary problems could have been handled by a <i>fix</i> provided by not-Mozilla, just like how DVD support was enabled in many distros (by downloading libdvdcss from France).<p>&gt; drop H.264<p>Believed the <i>hardware industry</i> would reverse years of designs based around H.264 is magical thinking. Software follows what the hardware supports (you are <i>not</i> going to get everybody to re-encode their cat videos). Anybody that believed that the <i>browser</i> market could trump the <i>mobile phone</i> market is showing they don&#x27;t understand how <i>de facto</i> standards work. When Mozilla was arguing against H.264 5 years ago, they were already several years <i>too late</i>.<p>Screaming at the tide to turn back doesn&#x27;t actually work, even if your intentions are good.<p>&gt; VP8<p>...was future technology. Once it was <i>actually released</i> by Google with the WebM container it became a relevant option (which was a good idea to support <i>in addition</i> to H.264 that was already very commonly used.<p>The nonsense <i>before</i> Google released VP8 was merely wishful thinking. Much like how solar power advocates like to include &quot;future improvments&quot; in their claims, claims that H.264 was not needed usually suggested using VP8 <i>while it was still vaporware</i>.<p>&gt; Today, Firefox does use H.264, AAC, and MP3 decoders from the OS<p>Which proves it is possible, and could have been done 5 years earlier to kill off Flash.<p>&gt; but AFAIU doesn&#x27;t expose any other OS codecs to web content.<p>They shouldn&#x27;t, in general. Adding another list that can be probed for browser identification wold be a terrible idea.<p>&gt; Do you think the current situation with EME DRM is &quot;H.264 all over again&quot;?<p>I think Mozilla is responsible for EME being completely accepted. Before announcing EME support, it was still possible to argue that EME was not supported by all browsers, an admittedly small reason for websites to not use EME. With Mozilla abandoning their mission (specifically principles #2, #6, and #7) to chase market share and become a Chrome clone, a major battle in the War On General Purpose Computing has been lost.<p>If Mozilla cared about the future of an open internet in the slightest, they wouldn&#x27;t support any form of DRM, with no exceptions. THAT is the place a principled stand should have been taken, not video codecs. Instead, Mozilla has chosen to let others pick the battlefield. The claim was that this was necessary to safe their market share. Well, that didn&#x27;t work[1].<p>Now that Mozilla has given up the fight against DRM, the problem will spread. The ebook industry already wants EME-like support.<p>[1] <a href="https:&#x2F;&#x2F;upload.wikimedia.org&#x2F;wikipedia&#x2F;commons&#x2F;8&#x2F;86&#x2F;Usage_share_of_web_browsers_%28Source_StatCounter%29.svg" rel="nofollow">https:&#x2F;&#x2F;upload.wikimedia.org&#x2F;wikipedia&#x2F;commons&#x2F;8&#x2F;86&#x2F;Usage_sh...</a>