Punk’d and Boiling Points are hidden- camera shows, so cameras are put in places that people won’t see them, like behind mirrors or on people’s glasses. You’ll notice that on Boiling Points, a lot of the people doing the prank are wearing thick black glasses and there’s a camera right over the nose.
On Viva La Bam and Jackass, I think they have someone taping far away so the people being filmed don’t know it’s a show.