I just finished a second instructional video with a talent in Florida (I'm in CA). Before we started filming, we got 6 sponsors at $100ea and 40 pre-orders at $25ea. This time around, I told him to hang onto the money from the orders and sponsorship to help with the plane ticket, hotel, etc. After filming and production was finished, I send out all the orders on my own quarter and put the ~$900 he owed me on a 'tab'. As I make internet sales, I reduce the amount he owes. The wording is clear in our contract that I would get my share of the funds due, and I'm sure that I will over time...but I'm only expecting about 100 sales a year and at that rate, it's going to be a couple years before he can pay down his tab.

What do you think I should do in this situation. I'm not going to LOSE money, but at the same time, I'm not going to GAIN any money in the short term. Should I bill him for the amount due or let it ride?

You should look back to what your written contract deal was and live up to it.

Hopefully you have a written agreement. But if you don't, hopefully both of you will live up to your verbal agreement as well.