I caught a You Tube clip of a 1973 performance of Cat Stevens doing Foreigner Suite. Remember watching it on ABC's "In Concert" series on WCVB-TV5 and listening in stereo on WBCN-FM 104.1 I was told that WCVB had to use a special Video recorder at WGBH that could reproduce the video and mono audio for TV and a second stereo soundtrack for FM I think in the early 70s didnt WGBH broadcast BSO concerts on TV2 and 89.7FM?