I got in touch with Jan, who made the initial report.
He thinks he was getting an 8 frame delay just through the projector.
So he had delays everywhere,

It is worth pointing out, that every piece of video processing equipment will add at least one frame delay, and possibly many many more.

By the time you get out of the projectors, you can get a perceivable delay.
In rock shows however - the whole sound delay things also confuses things;

Sound travels really slowly - only 300m/second. 1 frame is only 12meters!
So you move around the concert hall and sound and picture will move in and out of sync!