It depends on what the DVD is about. A workout DVD? There's nothing wrong in that. But it would be better to offer business building incentives. Like free 1000 visitors to his SFI gateway. Or if the DVD is a talk by a business Guru.
The only thing that is not allowed is cross solicitation. That means getting your CSAs and PSAs to join another business outside of SFI. Other than that, the limit is your imagination.