In exposes like the recent ACORN pimp videos, or Borat movies, or any number of television shows that specialize in these things.
I understand that these cameras can be tiny, but they can’t be on the person of someone who is supposed to be featured in the video, and they also need to be kept focused. But these are pretty commonly done, so I imagine I’m missing something obvious.
When a cameraman is required, the camera and cameraman are hidden in a blind of sorts, designed so as to attract no attention in the environment.
Others are done using a very small camera, or fibre-optic lens systems, which are set to focus at a specific point, and the victims are manipulated into sitting at the correct place.
Other tracking can be done with a remotely controlled camera.
Security protocols prohibit me from giving any details of other methods.
I haven’t seen the videos myself, but in consumer investigation type shows they tend to be hidden on the torso (typically in a button hole of a shirt the same general colour as the lens) and angled up slightly to point at the face of who ever the user is speaking to, with the transmitter and electronics hidden under the clothing.
I’ve also seen ones hidden in pens, sunglasses, etc. I think they generally keep them focused to a certain distance (you’ll notice hidden camera footage is always low quality anyway) that they expect the subject to be at. Finally, remember that more than one person can do the investigating; they could work in teams with someone to appear in the video and a cameraman.
It occurs to me on further reflection that suppose more than one participant is wearing a hidden camera, they could get multiple angles of the same scenes. This would help get a better final video in general, but would also help to include everyone in, as each participant could be filming the other(s).
I don’t think Borat used hidden cameras. They told participants they were shooting a documentary.
Very small cameras have greater depth of field so focussing is less problematic.
A lot of stuff filmed on streets just have the camera set up in a van with tinted windows. I know that’s how they did some of the Jackass stuff.
Such cameras are frequently hidden in a briefcase, purse, etc. which the person sets on a nearby end table or such, carefully aiming it in the right direction. And focus, etc. are set beforehand, to match the appropriate distance in the location.