Ok, took the time to watch it now, well, nearly to the end, couldn’t quite make it all the way!
The pragmatic answer is clearly to use public footpaths when they are quiet, when you can take-off and land safely, and without disturbing the occupants of the land they pass over. That’s precisely what I did yesterday evening to get these photos.
I believe beyond that there is no black-and-white legal answer, it’s a grey area.
A “right of way” is not just a right to walk along a footpath, it also includes the right to stop, enjoy the view, take photos etc. Those are from common and case law, I don’t think they are set out in legislation, so until a court rules, it’s really just speculation as to whether flying a drone from a public footpath is legally acceptable.
There is case law to the effect that there are no real restrictions on what you can do on a public highway:
I conclude therefore the law to be that the public highway is a public place which the public may enjoy for any reasonable purpose, provided the activity in question does not amount to a public or private nuisance and does not obstruct the highway by unreasonably impeding the primary right of the public to pass and repass
That judgement also states:
Further, there can be no basis for distinguishing highways on publicly owned land and privately owned land.
If you take the view that a public right of way (PROW) is just a public highway except without cars, then it follows that you can fly a drone from a public footpath so long as the activity is reasonable, does not cause a nuisance, and doesn’t obstruct the path. But you’d need a test case to be certain.
I think Mr MPW is erring on the cautious side because he takes the view that the drone community will get more acceptance if we don’t go around pissing off landowners. The counter-argument is that in England and Wales landowners have too much power over the general public, and we should be active and unapologetic in exercising our rights.
I’m in the second camp.