Dioxaz

Crap, my bad. I missed that little box saying: Thank you very much for your links. I think they should be added to the the first post and the older link removed. After indeed picking up one of the good pages you linked me, it's much better. So at least, my issue is solved when creating a new profile. I also took the opportunity to test out Level 5.2 MP4 files and they work too!! But there's one caveat, hardware acceleration doesn't seem to work (it looks like I forgot I didn't have hardware acceleration back when I was still using XP). This explains why Level 5.2 MP4 work too. I wonder if acceleration is possible with the Adobe Primetime plugin. It looks like it's my older profile that was causing MP4 not to play anymore (the plugin was installed automatically). I guess I'll see that later.

Hello everyone. I hope I'm ny bothering anyone with the silly request I'm writing below. I used to be able to play MP4 HTML5 streams with my older Firefox 52 under Windows XP. Now it seems that I can't anymore no matter what I try. The latest thing I attempted was starting from a brand new profile. I'm on Firefox 52.9.0, Windows XP SP3 32-bit with the POSready2009 registry hack. I swear I followed all instructions of the first post without missing any single step. Every about:config option. The primetime_gmp_win_x86_gmc_40673.zip file unzipped in the right folder. Still no dice. I may have missed something obvious but my brain is currently (at least at the moment writing this) unable to process what it could be. Included are screenshots of about:config, about:plugins and the result of the https://www.quirksmode.org/html5/tests/video.html page. Not shown in my screenshots, media.eme.enabled is also set to true. The Adobe Primetime module is indeed set to Always activate. In fact, I hardly need it in my everyday browsing as I rarely use my XP install nowadays but I wanted do a test regarding playback of level 5.2 MP4 files (Twitter transitions all their transcoded GIFs to level 5.2 MP4 and this cause problems for Windows 7 and 8.1 users but I wanted to test it under XP too). Not even regular MP4 streams play at the moment (Youtube, Twitter or anything else, as the html5 test page suggests it). Edit: it looks like the https://www.quirksmode.org/html5/tests/video.html page is no longer reliable as even my usual Firefox 70 within my Windows 7 x64 installation fails to show the videos of that page (all URLs lead to a 404 error, the maintainer of that page NEEDS to do something about those broken links). For the time being, you can't trust this page anymore.