If a cabin crew member exercises the authority devolved from the Pilot in Command to order filming to cease then you are in breach of the Air Navigation Order if you continue and are committing a criminal offence.
I'd suspect that not a lot of passengers are aware of that.
And just how many passengers would be aware of, or even heard of, the ANO at the point of online booking or being briefed regarding at the point of check-in, boarding or during the pre-departure safety briefing?
A scenario of common sense prevails, don't endanger the aircraft, don't behave like a total idiot etc. but on board video movies are all over youtube, the web, so, common sense prevailing, what could possibly be wrong with filming on board?
So this, and many other, video(s) is illegal and should be removed from the web forthwith?
https://www.youtube.com/watch?v=Lqh8e2KYIrU