Get the tab for this here:
It’s not exactly like the video, I kind of made it up as I went along and didn’t always get it right rhythmically, so the tab is better.
This is a a study in alternating thumb fingerpicking. Try it like this:
thumb and index only
thumb, middle, thumb, index
thumb, ring, thumb, index (how I do it in the video)
Tremolo: play the open first string rapidly three times: ring,middle,index
Angus Young hit on this cool lick a long time ago – he used it in the live version of ‘Let there be Rock’ back in the seventies, and he recycled it for ‘Thunderstruck’ in 1990.