it discovers audio, but unfortunately sucks with blob:https//... video handling.
in other words, it tries to do things VLC does best way.

Находит, но скачивает только то, что загрузилось и к тому же отдельными файлами, это же можно сделать штатными средствами, так зачем перенагружать браузер ненужным расширением?

Doesn't work with Vkontakte. That's sad...

This may have been useful a couple of years ago. But these days, most media is "streamed" in a bunch of small segments, rather than one complete file. I tried using this extension to capture such streaming media—but all it did was detect each segment (which you can already do with FF's developer tools, BTW). So I can't say I really see the point of it.