[old_tv_nut]

First of all, they did not shoot 24 frame per second film of a 60 field per second TV - the result is a terrible mess of flickering shutter bars.

Also, it is extremely difficult to get the exposure of a CRT correct with respect to the surrounding scene - you have to make the picture much closer in brightness to the surrounding light than usual, either by turning down the TV or using brighter lights in the studio; but then the TV picture gets washed out by reflected light. Normally TVs are viewed in relatively dim surround. This was especially important in the home for CRT sets, which did not have very good contrast due to reflection of room light. The eye made up for it by simultaneous contrast between the gray "blacks" and the brilliant highlights - but you couldn't photograph that successfully because the resulting film would not be able to produce the contrast range between dim room light and brilliant TV highlights. Also, the movie image would not fill the viewer's full field of vision the way a real room would, so the effect would not be the same even if the film had the same dynamic range as the original scene.

Some movies with much larger production budgets would have TVs modified to run at 24 Hz and have special video sources to drive them, but this was relatively rare. The optical effects to superimpose a picture were much more readily available. And finally, if they weren't spending the money and jumping through the hoops to use real TV pictures, they also wouldn't do any special black and white process, but just use the same color film they were using for the rest of the movie.