I don't know much about Reggae history, but watching this German film (although in English), I thought it was made much earlier than 1978. Memory fails, I guess, even though I was a young adult then. Bob Marley was mega-famous by this time, and inspired many of these musicians, so duh. It was shot in 1978, so don't expect 1080p video. It's very watchable, though, and the soundtrack is remarkable, as this was not a lavish production.
Most of this film consists of live performances (and a couple of "fake" studio lip synchs of cover songs) interspersed with interviews. The interviews are the smallest part of it, although they say a lot. I love the concept of the Jamaican "sound system", a Reggae rave or street party, where the DJ brought everything required to turn anyplace into a party.
I most enjoyed the amazing performances by the band Steel Pulse, esp their 1978 single, Ku Kux Klan. Really great music of any genre and a wonderful anti-racism song. I didn't know the KKK were across the Atlantic, but then again, why not? It was brave of them (and Island, as it was their first single with the label) to release this single, even though they had to know it would get little to no airplay, then (or now, likely). Steel Pulse was in the first Rock Against Racism concert and were a great supporter of that movement.
Even if you aren't a Reggae fan, it's mostly good music with great insights of the time, and I presume priceless for the Steel Pulse, and other, footage. I loved seeing all the vintage equipment, fashion and style from that time, in that time.