I believe this comes from when there were lots of older cathode ray televisions which would give out an ocolating mains hum at 60 Hz, which the chipmunks did not like the sound of.
I have LCD TV's and PC monitors since i kept chipmunks and this does not bother them at all. I believe they are OK with LCD screens as many a time mine will sit on top of the monitors for the warm when they're on.

I am careful not to have the sound up, i use head phones, as my chipmunks will be in bed by early evening, and i don't think it's fair they should hear all strange noises coming from the TV speakers.
Modern flat panel monitors and TV don't have valves in them so should not give off that mains hum, a lot now run at 100 Hz or above.