Here's the answer.  In the 50s and 60s and even early 70s a lot of bands got their exposure on television shows.  A lot of television shows actually went out and would cover a band or singer performing live.  There were some television shows like the town hall party (Johnny Cash 1958) that were just a live performance broadcast on TV.

In the mid-70s bigger more extravagant arena shows became the norm.  Bands didn't really appear on television shows that often and when they did they often lip-synched.  You have examples from the mid-70s such as Skynyrd in England where the BBC actually filmed it with film, the last waltz by the band in 1976 was film not video, as well as the AC/DC from 77 through 79 and Nazareth etc. all the BBC shows were all television performances where they played live.

Video cameras were not the norm really until the mid-80s.  That's what makes shows like Styx at the height of their career and journey and a few other bands really hard to get on video playing live because they were playing arena shows most of the time.  There are videos especially out of Japan in the early 80s that were really good quality but the stage was really lit up and that helped a lot.

So when I saw this particular show it brought back memories because I saw them in 1980 on the Cornerstone Tour and they absolutely blew my mind.  I would rank that performance I saw in my top 10, and I saw a lot of bands in the late 70s early 80s.  This tour was what they did the following year yet they play a lot of the same songs with the exception of boat on a river (which I have from an 83 show that I will be putting up) and while the quality wasn't stellar, finding good quality video from 1981 is rather tough.

So this is why I'm putting it up.  Maybe it'll bring back memories from some other people and they'll excuse the poor quality and just enjoy it for what it is.  Also on some of the clips you need to be patient because it's just going to seem like it's a gray screen, but the television cameras they were using really were not conducive to lowlight use.  And when there are times that the screen is just gray it's because the lights were low and they will eventually come up and you'll see the performance.