Didn't they change it so it's much more similar to how Chrome extensions work? Shouldn't it in fact be easier now to have an extension work in both Chrome and Firefox? The Mozilla wiki page on WebExtensions even says "Much of the specifics of the new API are similar to the Blink extension API."
The Chrome extension used should work just fine with Firefox, but Google would rather try and force vendor lock-in. At this point I just use Jitsi, it works every time without any browser extensions to do a quick video conference or screen share.
When it launched in 2013, Hangouts used an NPAPI plugin that worked in most browsers. In 2014, Google ported Hangouts to WebRTC for Chrome only because it relied on non-standard WebRTC features only implemented in Chrome. Note that Firefox did support WebRTC at this time and Mozilla in fact developed its own WebRTC video chat service in 2014 called "Hello" that worked in Firefox and Chrome.
In 2015, Mozilla announced that it would drop support for NPAPI plugins in 2017, giving websites using NPAPI plugins ~18 months to switch to a non-plugin solution. When the NPAPI deadline came, Google announced the Hangouts would stop working in Firefox, they were "actively working to develop a solution" for Firefox, and until then Hangouts users should use another browser:
It's 2018 and Google is still working to support WebRTC in Firefox, but they're definitely working on it. In fact, WebRTC Hangouts does mostly work in Firefox now, but only for users with a G Suites enterprise account whose admin has manually enabled Hangouts. I don't know why.
"Hangouts Meet" is a different product using WebRTC whose support for Firefox is still in development.
I've been documenting this saga on this Mozilla wiki as part of the NPAPI deprecation and Win64 Firefox rollout:
Thanks for the info. I totally forgot Hangouts was still using an NPAPI plugin, and I didn't realize Firefox dropped support for those too. Doesn't explain why Safari wouldn't be supported though, as Safari still supports NPAPI plugins.
