As you can probably tell from his accent, Berry is working in London, so its worth noting that the rules he shares about public photography vary from country to country. (You can find a good rundown of what’s permitted in the U.S. in this video from PDN, but our laws seem to be quite similar to those of our friends across the pond.)
It’s not clear how much time Berry spends taking pictures before the first security guard comes up, but he’s approached no fewer than three times throughout the video. Each time it’s by private security, rather than police, and the confrontations all go fairly smoothly, aside from the fact that, you know, it’s not fun getting harassed in the first place when you’re trying to take a picture.
The video concludes with a lengthy interview with a police officer about the laws that protect photographers in public, as well as the unwritten best practices that photographers can follow. For example, while it’s technically legal to photograph people in public, if you choose to follow someone, at some point you may cease to be just a photographer and could be bestowed with the title of stalker. There is a different set of laws for that.
The good news is that private security is not permitted by law to confiscate your camera or force you to delete photos, even if they catch you on private property (although, in that case, they can certainly ask you to leave).
The moral of the story is simple: Be aware, be polite, and don’t be afraid if someone asks you what you’re doing — that’s within their rights, just as it is within yours to take pictures in public.