[tptacek]

Not really explicitly, but implicitly they won't pay you to travel to conferences nobody has heard of (there was a list of acceptable conferences for the benefit at one point --- it covered pretty much all the well known conferences in our field, and there were a bunch of them).

Part of the idea is, the good conferences do some of the vetting for the bonus for you. They discourage "touring" talks, and have a high bar for inclusion, so if you're speaking at e.g. Black Hat, CanSecWest, Recon, and Toorcon, there's probably a reason that's happening and NCC is probably very happy about that reason.