Just wondering if you figured anything out. I am assuming we are sure it is recordmydesktop, and not ffmpeg causing the problem...
In truth I did nothing further on this.
I will have another look .... I have a suspicion it may have something to do with the frame rate .....
It seems to me that for whatever reason my recording is not getting every frame ... or even only dropping an odd frame. I seem to be getting only a frame every few seconds! On playbac one frame maybe every 7 secs! With setting of 9fps.
I have tried adjusting frame rate and colour depth to no avail ---- even turned off compositing to see if that would help. There was a time that this app had a problem with some colour depths, but that would appear to be fixed.
The app is in binary form and is inaccessible for all practical purposes.
Not sure where to go from there.