I took a screen recording to illustrate this issue.
The first 30sec show normal operation on RTSP
at 0:40 you can see the "offline" overlay overtop of the moving video
at 0:48, you see me change layouts to force a screen refresh, which does get rid of them
the last 12s is showing another issue that I made a separate ticket for.
**EDIT: I actually just switched back to RTSP after typing this up and the "STREAM TIMEOUT" error overlays persisted on the two black bottom. As before, changing layouts clears the overlays, but it leads me to believe that the issue is unrelated to the addition of MJPEG.
Aside from these bugs, kudos on finally getting MJPEG support in the client. From what I see, it's far less CPU intensive than RTSP.