To reproduce this, you need to have a large queue of files, let them all download, and at some point, this will happen.
x265
That doesn't surprise me, since the YoutubeToMP3Process and/or YoutubeToMP3Service
keeps getting stuck repeatedly during the Max analysis (for me).
So the workaround will probably be to download smaller amounts or restart SF in between.
I assume that no forum user can change/bypass this, so a ticket
(SF Feedback) would probably be more appropriate.