Multichannel Television Sound (MTS) became a technical standard in the mid-80s. Ten years earlier, TV show concerts were sometimes simulcast over an FM stereo station. The brilliant, forward-thinking innovator Walt Disney had experimented with stereo for TV way back in 1959, only one year after stereo records were introduced.
In addition to stereo, Walt gave letterboxed presentations a try on standard television sets. He promoted Technirama 70, which is explained here.