Maybe Nextcloud should get its own Nextcloud-browser-plugin to enhance the video support?
so if no plugin is installed, only browser supported files can be played and with plugin installed, videos will be played through this plugin.
So we’d need a client side plugin, as in, a plugin for Chrome, one for Firefox etc? It is an idea, though there are probably legal problems - the codecs are patented and all that so unless we make it a proprietary, paid plugin, I don’t think this is legal