IT NO LONGER WORKS AT ALL, does not appear to try, just says cannot merge streams but does not even do the usual assembly.

It makes me very sad that this extension has been ruined by the developer. It used to be a really nifty extension capable of saving anything. While it can sometimes save SOME videos from YouTube the extension with companion app make it so slow that it is not practical. We are talking HOURS here. I am not surprised that the developer has given up. The least they could do is stick the source of all versions on GitHub so someone else can try and fix it. Thanks for your previous effort.