2 video loops?

Hey guys, this has kept me up all night.

I want to play 2 video loops:

Sequence 1 (frames 0-50 of a video file) loops continually until...

Sequence 2 (frames 51-100) is triggered by a noise (clap, shout, etc.)

After Sequence 2 completes, patch goes back to looping sequence 1.

I have to turn an assignment in this afternoon. Would greatly appreciate the advice and/or patch .