I am not a lawyer. I hope you consult one before you sign anything. The lawyer is the only person who will represent (for a fee of course) your interest. I’m saying this because it all sounds a bit dubious: not only is the fee a high but also they’re 60-40 sounds weird.
Regarding the high fee, okay, I could see that, if your footage is (for example) a crowded kids birthday party, where the cost of producing it would require 15 kids on a day rate, plus 10 adults on a day rate, wow! that’s expensive.
Regarding them taking a cut, I could see that if they are aggressively soliciting buyers. In which case, I would think they are more akin to an agent, in need of an option agreement.
Hope that makes sense.