Use a lascr connected to the flash. They were popular devices that people connected to a slave flash in the film camera days. I paid about a dollar for it and connected it with a flash extender cable.

There is going to be a problem with video. On older camera sensors the global shutter can work some of the time but on the newer progressive cmos sensor you may capture only a few scan lines because the shutter opens and capture a video frame in say 16 millisecond and the flash duration is 1 millisecond. Bad idea.

You need to get the right equipment.

Quote Use a lascr connected to the flash. They were popular devices that people connected to a slave flash in the film camera days. I paid about a dollar for it and connected it with a flash extender cable.

Actually..... that wasn't a half bad idea, an external "trigger"; that's thinking outside of the box, I have to give you some creds on that.

I guess I'm really looking for something like this:

https://www.nicolaudie.com/en/slesa-u9.htm

Assuming it works like this external media player:
https://www.amazon.com/VonHaus-1080p-Mini-Media-Player/dp/B00NEIYBK0/ref=sr_1_6?ie=UTF8&qid=1484797236&sr=8-6&keywords=media+player

Where you just save your video to an SD card and plug the media player into a projector and it starts playing your videio in an endless loop.

The added benefit would be to trigger the lights via DMX signal.