sequencing video challenge (sci/art collaboration)

original topic https://cycling74.com/forums/index.php?t=msg&goto=86695&rid=4712&S=2a2a0d1efe4b56c2f91e3620f62d0f56#msg_86695
Doc Op you were right, as soon as I triggerd four imovie objects the whole thing went pear shaped. I was really dissapointed that even the MIDI went in and out of tempo. The videos drift in and out of sync. the MIDI does go back to the correct tempo (after a few seconds)

Having a look at sync~ but I have just realised that the imovie has no audio! doh

I thought this one was going to be simple but is proving a headache.

for anybody reading, this is the challenge. (simplified)

I want to trigger four videos (with audio) of different lengths. the lengths are related musically i.e video 1 is 8 beats video 2 is 9 beats and so on
they will all loop but be sequenced from the same tempo base. polyrhythmic video if you like.

A four track step-time sequencer that allows each track to be a different length and can loop indefinitely could use single note on for the triggering of each video. this is where I am stuck!

I could maybe generate this behavior using logic audio and a VJ app like Grid pro, leave the audio in Logic and trigger the video via MIDI. No doubt I could capture the result and show that , but I really want this to run in real time so that we can all hear (and see) what the generative permutations sound like after a few hours. The nature of the polyrhythms means that there is no repeat point in the music for hours and hours.
If I get to exhibit this I will credit all who helped! Looks like I am looking for a sci/art collaboration contact me off list if you are interested, I am in London.
Thanks for reading.