Rats. No suggestions yet. I was afraid it couldn't be done - just hoping that some of the technical gurus on this site could figure it out. Still hoping ...
I also got bad news from
Phototrap. Here's what they say about the MkIV ...
"
The Mark 4 does not have a wireless infrared remote to activate the video like
the 7D and the 5D's. The photorap M#88 will trigger the video with the infrared
remotes and the length of time it runs can be set from less than min to 26 min's.
So to answer your question it will not start and stop the video on the MK IV."
At least anyone with a 7D or 5D can do it. I don't have one of those :(