I've only done it a couple times with Tina Zampa in the past. She charged an arm and a leg for it but it was worth it. She had the kind of gargantuan physique that's rarely seen in FBB anymore. Had to get all the content I could while she was on the scene. As far as the custom video she filmed it exactly how I asked and sent it to me when she said she would with no hassle. The only issue was it wasn't in HD. One video was pretty low quality but still very watchable and the next clip was much better quality but still not full HD.
Colette Guimond had once advertised that she offered custom videos so I jumped on that opportunity without hesitation. When I emailed her about it she replied back asking me how much I would pay for it. This annoyed me a bit because why would you offer a service and not put a price tag on it. Nothing ever came of it after that.
That's about it really. A FBB has got to have a "WOW factor" physique to get me to even consider buying a custom vid from her.