Debian, stable, git build of Master from today.
(e 8 a 4bddef4ff) (I put spaces because the hash was auto-referencing another bug report.)
I'm not sure when this used to work, and am not sure how to diagnose it.
Playback in the VSE, while working, will periodically get into a state where it no longer plays. It will do a frame, then stop, while "pretending" it's still playing. The frame will progress only one forward then stay there, and the FPS stays showing in the corner of the preview.
Reloading blender will get it going again, but after some time it might happen again.
I don't have a minimal .blend to demonstrate this yet, but here is a video showing it.
Any time the play/pause are toggled I am either using the mouse or hitting spacebar.
(Also, I forgot to enable mouse-cursor in the recording, but you can see the red indicator of clicks, except when I'm using spacebar to toggle playback).
If I change the Audio Device from "Pulseaudio" to "OpenAL" in Preferences after opening. The problem didn't appeared after, but I have to check more and in a longer duration.