For every single video that I shoot, every participant (or individual appearing in any manner) has multiple sets of forms that need to be filled out (i.e. legal forms and model releases) and they must submit proof that they are over the age of 18 and are fully aware that these are "adult" videos. It totally stinks, but unfortunately it has to be done even if the individual only appears for a micro second.
The negative side of living in a country overpopulated with Phonemen.... sorry, I meant lawyers.