How to reverse an M

Hello,

I have an MC that contains a video that’s 175 frames long. I’d like it to play forward and backward endlessly but I can’t figure out how to reverse it so that I can paste the reverse onto the end of the forward clip or how to script it so that when it reaches the end of the clip it plays itself backwards. Seems so simple, yet I can’t get it.

Much appreciated,
Llyfre