Using public domain footage is one way of using the medium of collage, but I think in this case back in 1982 we were trying to make a different point, where it was necessary to use footage expressly without the permission of its corporate owners (see video below).
Intellectual property law does not address the fact that advertisers are overstepping personal boundaries by colonising personal psychic space with their repetitive messages of eroticised consumerism. I think we really have to question in whose interests intellectual property laws are constructed.
Do we accept that the corporations who produce this material can claim to own it once it has become a part of our subconscious? Who exactly owns the contents of our minds?