This is a different problem from the one I posted 22 days ago (Jaksta doesn't dignify it with a date) and which remains unanswered.
For the past many months I've been downloading live YouTube streams via their URL, but can no longer and I think it may be since the last "engine update" - 18.104.22.168 had been working fine up to then.
It shows as Extracting but morphs into Complete (Errors).
I do hope that Jaksta Support is still active.
A new Jaksta extraction engine update seems to have fixed the problem.