Fucking great talk, Flash getting into the real nitty-gritty technical aspects of how he created his style of DJing. Ignore the shitty hosts.
The fun part starts about 13 minutes in, demo starts at about 43 minutes in.
Also, I'm on a bit of a hip-hop lecture binge, I'll post some more videos like this in the comments.
Kanye interview from 2013, mostly on J Dilla and the intersection of fashion and music. Questlove on the challenges of drumming for D'angelo Young Guru on the business of engineering and drawing inspiration from places outside of music (truly horrendous interviewer, sensing a pattern)
Hip Hop Evolution is an excellent dive into the foundation of hip hop, and how it became a Thing. From Cool Herc's original party, right up to Fear Of A Black Planet, this series is fascinating. It also nails my favorite period of rap, so I was singing along with everything they played! My wife stared at me wide-eyed through most of it...