Nothing special...manual editing of mp4 file in Ableton arrange window. Track 1 is movie file and track 2 is audio to listen to footage against. Listen to the same few beats repeating over and over while I slide the movie footage back and forth until it looks correct to me as it repeats. Then move to next beat..repeat this for many hours and you get a 1 minute clip to share with the satisfaction of being done by hand.