I've spent too many hours at solving this simple issue...
...but I've found the cause, and the fix

Description of the problem:

  • recordMyDesktop "forgets" / "cuts off" the last part of the screen capture
    The last frames are -somehow- skipped

I've mounted my /tmp folder to the RAM using fstab (to relieve my SSD).
/tmp is the default working dir of RecordMyDesktop.

After recording many frames, the /tmp folder's usage is 100%, thus full. Although recordMyDesktop cannot write to the /tmp folder any more, he doesn't show any warning / notice. To solve this issue, simple change the working dir to a physical disk location. I added the /temp folder for this purpose.

I don't have experienced the following myself, but it seems obvious to me that a full physical disk will also cause this problem. To solve that issue, remove obsolete files, or buy a new Hard disk.