There are several brief scenes in which this technology is referenced. The camera is on the outside, and a screen connected to the camera is showing the outside to those inside.
The first scene is the one in which Dr. Heywood Floyd's transport is descending on the Moon. (quote 1, p. 53)
In the second one, the temporary facility built next to the monolith on the dark side of the Moon contains a TV screen showing the monolith, surveilling it at any given moment. Dr. Floyd is among the ones watching. (quote 2, p. 76)
The third one references cameras that show the outside of the spaceship Discovery to those inside. This is mentioned in the chapter that details Poole's and Bowman's routine aboard the Discovery ("Cruise Mode"). (quote 3, p. 99)