Firefox ESR implements Encrypted Media Extensions (EME) by initially having it turned off, but when visiting a website requesting its use popping up a user dialog to confirm enabling it. From then on, EME is enabled generally in the web browser.
Please add a file /etc/firefox-esr/pureos.js with same content (essentially two lines, but preferrably including the commented documentation as well) as was applied to PureBrowser: https://source.puri.sm/pureos/packages/firefox-esr/-/commit/105f0d1
This is important as we do not want to implement any browser prompt to install an EME plugin.
@jonas.smedegaard Did a user report this? Or is this bug from your own sleuthing? :-) I ask because sometimes the FSF rewards users who report freedom issues with GNU Bucks and there may be some at stake for reporting.
The plan that was devised consists of two steps;
I reported this issue on my own (not driven by reports of others but from my prior knowledge in maintaining PureBrowser and therefore pretty exactly knowing how they differ).
I was not the first to report this issue more broadly in PureOS, however, but as far as I am aware the first to a) report it in isolation (not conflated with other issues, each potentially needing different action and therefore unhelpful to track together - see e.g. T891 and T902) and b) report it specifically against the "Firefox ESR" branded incarnation of Firefox (as opposed to PureBrowser which is arguably same project - see e.g. T11 and T147 and T269).
Please note that it looks like adding /etc/firefox-esr/pureos.js is only masking the problem. The underlying implementation would still be built in the package and available in the source code. This has already been mentioned in the last paragraph of this comment: https://tracker.pureos.net/T902#16752
This issue is considered solved in PureOS.
It is true that the solution used for PureOS is not ideal, but it is effective: Users cannot accidentally or sloppily make use of the EME implementation included with Firefox ESR as shipped with PureOS, because it requires manually editing plaintext files to enable that functionality.