Laws Governing National Contests

[Small Business Solutions]

I am working in the state of Hawaii. One of my clients is thinking of doing a national contest with his product. The contest requires each contestant to make a video of themselves demonstrating the product. I want to know if this is legal, because I have noticed that most contests say that you don't have to buy anything to enter the contest. In this case, it is likely that the contestant will need to purchase the product or borrow it from someone who has purchased it.

Thanks for your help in this matter.