Check out the Get Thrashed: The Story of Thrash Metal trailer which features the music of Exodus, Slayer, Anthrax, Ulysses Siren, Suicidal Tendencies, Response Negative, Exit to Eternity and Nocturnal Fear.
Take a look at a section from the film Get Thrashed: The Story of Thrash Metal. This piece is titled "Thrash Metal is Born".
In this clip from the documentary, the connection between thrash metal and hardcore punk is explored. Combining the two genres seems like a no brainer today, but in the 1980's, this "crossover" of crowds & music styles created tension, fights and very often, real violence at shows which featured bands of both genres.