From the Reranch refinishing web site: TV Yellow was developed by Gibson in the early '50s to allow a "white" guitar to be played under the intense light required for black and white TV without the color overpowering the camera. ...
Absolutely, totally false. The whole story got started because of an unconfirmed claim by some unnamed guy somewhere who said he once walked in on a live TV production in the 50s where everyone was wearing yellow to show up white. It may have happened once, but I can tell you from first hand observation that this was never a regular practice. Besides, NBC and CBS started broadcasting in color in 1954 even though there were almost no color sets.
As if Gibson would do this on their cheapest student model (3/4 scale only for the first couple of years) anyway. They never expected anyone to play it on TV.