Start and End Time do not work on replay
The start and end time that you choose for your video will activate when the page with your player is loaded and the video initially plays.
However, if your viewer chooses to replay the video, this starts at 0:00 and ends at the actual end time.
Unfortunately, this is something that is out of our control since there is no way to intercept YouTube's replay function. Once the video has ended, basically, control is still with YouTube and MonkeyPlayr cannot get it back.