Hi I'm a bit confused.
Are you selling leads to them or are you offering to do their ads and charge them per lead
Do you appear in the video? If not, I think that would help - make it more personal in general. Just like I would really look for a personal relationship with my dentist and probably stay with them for life, I think you should also add a personal touch regarding FB ads.
Maybe also talk to a few dentists in your area and see what they think about acquiring FB leads for their practice. With their input, you can then scale onto FB, but before that you probably need to go the old school way of knocking on doors and making calls.
Also, what bramburn asked - it's not that clear what you offer. I think your idea to work with real businesses and starting with dentists is great, but your overall approach needs a bit more input from your relevant audience.