So two parts really- any recommendations of anyone particularly good at handling the being filmed side?
And second, any advice in general about how a filmed punt might differ from a “normal” one?
Part 1.
Find an SP who has the 'Being Filmed' tab ticked. However, you need to be careful with the 'Being Filmed' tick - even if it's in their 'likes' list, as it can mean anything from being a webcam performer to 'wearing a mask' to using their own equipment and editing it themselves. A little research finds the ones where you can just let the camera run (and have a little handheld as well - for those 'special' shots).
Have a glance at the type of media they have; photos, video - does it seem to fit what you're looking for? Send them a message asking the basic question. Generally, the type of SP should be fairly uninhibited - you'll get a good idea of this from their profile.
Part 2.
Holding a phone, directing, and being 2nd lead performer is very hard, so you're not just having fun... you're working as well. Also, try to just set it up, press record, and let it run.
Light is important, especially for video. Background noise is best avoided, especially for video.
I would add that it really should be for personal use only, both legally, and so that we can be trusted.
Decide where to keep the footage safely. Don't keep it on that USB stick that last year's holiday pics are on!