That basically means you will NEVER get paid. Take money up front or walk away. People who have been doing crew work a long time never take back-end jobs because they know that it will never pan out. Even if the movie were to make money (1% chance?), there's sharks out there who will skip out on paying you, never give you a complete written accounting, etc. In fact, if you don't have a bullet proof contract you are basically powerless to do anything about it. Shady producers know this. Only a lawyer can know the in's and out's of these contracts.
Just tell them what your rate is for camera work and see if they meet it. What you do for them would be "work for hire," and likely just covered under a deal memo rather than a complicated contract. Basically you need to know in the deal memo is your work and pay schedules, whether you are an employee or independent contractor, what expenses (if any) you will have to outlay and get reimbursed for, if any travel and accommodations are paid for, and who is supplying equipment (you or them). I believe most camerapersons have a package rate when they use their own cameras, and get paid a flat per diem rate, and maybe overtime.
Also when a producer promises you some of their points that they claim they are entitled to, think about what happens if they breach their contract with the investors, and as a result they are never entitled to ANY points. Then your points will definitely be worthless. There's a million reasons not to accept a points based payment in this shady business. Get paid up front.
