AC/DC Song Questions

This is a 3.32 minute video response from David MacKenzie on Apr 21st, 2009

Question:

"Roccafamilia23 asked "Hi, my question is about the acdc song lesson with Dave Mackenzie. Okay after the three chords are played and after the two notes and the string bend, I'm having trouble seeing what he's doing on the fret board. It looks like he's hitting the fifth string first fret and then the sixth string fourth fifth sixth and seventh sliding his fingers back to the fourth, but I can't tell for sure. Could you please explain in detail this third part of the song to me. Thank you so much. fellow guitarist, Daniel.""