Originally Posted by SpicyM

They are the producers and they need to issue a signed exclusive licence to you - they sign it and they can easily mail it to you.

Make sure that there is a clause about providing copies of their IDs and that they grant you the permission to provide the copies (their personal data) to third parties in case of verification. Having the models hold a sign with the date of shoot and "Exclusive licence granted to YOUR NAME" in the beginning of the unedited footage is a good way to quickly prove that it really was licensed to you without providing copies of the papers to third parties.

The licence should containt a detailed description of each scene, personal details of both parties, the definition of what you can do with the content and all the statements needed.

Easy.