There are already two existing solutions for this:
1) Use the Restart module, which has a param you can trigger to restart any modules connected to its input(s). This is very efficient in your case, because it serves only to reset the Play index to 0.
2) Instead of separate images in the JpegFolder module, use a video file with the VideoFile module. Then you can trigger the Goto Start param, which you can use to rewind the video.