That video is them playing Whiplash which is track 6 from the 1983 Kill 'em All album. If that video of them playing that song is footage from the actual concert that you watched live in Germany, then that helps narrow it down to early 80s when the song was played. That cuts out decades of possible songs. I still have all their old albums on cassettes in a shoebox from growing up. I also have some live and unreleased garage and live stuff recorded on cassettes like them playing an early version of Devil's Dance before that song was released. It has been decades, but I don't recall any of the songs I have being a recording of a song called Kill Them All. I'll see if I can find a cassette player around here and give those old tracks a listen to see what all is on them.