Of course, the participants must be legal adults -
reaaallllly make sure you verify this even before discussing your production plans.
You'll need a work contract and release forms which state the person agrees to be filmed/videotaped and waives all rights (or whatever agreement on rights you desire).
If you distribute the video, you'll also need Federal law compliance data intake form for compliance with 18 U.S.C. 2257 et seq and 28 C.F.R. 75 et seq - the participants individually fill it out and it is signed by you and each of them. With this data you will also have to collect and retain copies of their state and/or federal IDs and SS card. (you make copies of the originals, not accept copies of IDs)
Note, you have to make copies of the documents and maintain a record keeping system because the information has to be made available on demand.
Imo, you should also consult an attorney to make sure there are no local or state laws against the production or distribution of pornography.
Regarding testing, I would contact
AIM for some guidelines about safety, but, if not working with established couples, I recommend condoms. There are brands of condoms that are so sheer, you may not see them, unless you are using digital and then you see everything. (maybe too much

)
Good luck!
