Good Documentary with shortcomings
Overall good, thought it was a BBC special with most praise lavished on Brit Bands. We shouldn't dwell on what is or isn't metal, this chnges every decade or so. Surely EARLY Aerosmith 1972-1979 put out more kick ass songs that definitely fit into the "metal" category than crappy groups like Warrant & Poison. Unfortunately the addition of the dreaded keyboard or piano (horns) excludes many bands from contributing to this documentary.
Inaccuracies: The first "power ballad" came out at least 10 years prior than stated. Nazareth's Love Hurts. Zeppelin's Thank You can qualify.
Anthrax & Public Enemy the first to break down the rap/rock barrier, not quite. Try Aerosmith & Run DMC about 5 years earlier with Walk This Way.
Enjoyable viewing but shouldn't have been as narrow with band selection and so "UKcentric".