You can get it from sponsors, buy it or license it through something like AdultCentro.com lets say (Mech Bunny Tube script has this built-in).
As far as scripts, your best choices are KVS, Mech Bunny Tube, and
Smart Tube Pro.
Your first choices for advertising should be:
Adamo Ads (very good)
Click Papa, and
Ero Advertising