BDSM is a term that can be used to describe many sorts of non-conformative or 'normal' sexual relationships, but there is one consistent rule regarding BDSM, and that is mutual consent. Pedophilia IS NOT part of BDSM, as pedophilic or predatory relationships including minors cannot be mutually consensual by nature.
There are, however, definitely people who may play out pedophilic fantasies with other consenting adults. It is also important to note that this sort of play/dirty talk could also be incestuous fantasies rather than pedophilic, but could just be both.

Does it usually invove such pedophilic talking???