Here in NY City female toplessness is legal, but I don't know about LA. There is an arcane 19th century law here about disguise with intent to defraud, which was technically used against transgender people in the old days and more recently against Occupy Wall Street participants wearing Guy Fawkes masks. And it seems here, it's not about "nudity," but about activity.
Also, you talked way way too much to the police, as they say in Miranda warnings that information, no matter how innocuous it might seem, can and will be used against you. You are only obligated to respectfully ask if you are being detained or under arrest, or if you are free to leave. And we're talking about the police here, believe me, you are in a database now, and he probably checked for priors. This might come back to bite you.
And, not to be critical, but couldn't you find an appropriately less public place to make videos or photographs? They could've validly busted you for filming or photographing without a permit. Those things are highly regulated. On a practical basis, if you are going to do this sort of thing, you need to be more professional about it.
