 In general, many of these performances will have only have been shown a very limited number of times on TV and in some cases only once.Very few of these concerts seem to have made it to legal DVD (such as the Bill Bruford, both John Martyn and a sample of AC/DC).Bootlegs exist created from original TV (although very few domestic video recorders were around at the time) and radio broadcasts (through cassette tapes) as well as subsequent repeats.