You can find some great clinic talks, quality X and O stuff, and other solid football content on YouTube. A lot of times, a coach on Twitter will come across a great sound byte or snipped in one of those old videos and redistribute it.
Case in point here is this Nick Saban talk from a clinic years ago talking about split safety coverages. Anytime Saban is talking defensive play, and especially defensive back play, you know it's well worth your time.
Almost 17 minutes in, Saban shares something still relevant today to defensive back play by explaining how defensive backs can maintain position on a receiver.
"Look guys, backpedaling is the most overrated thing about playing in the secondary in my opinion."
Keep in mind, this is well before the spread and Air Raid has taken over college football.
Saban went on to share how he used to teach the backpedal until he had a special player that just couldn't do it. So he started to teach the half-turn technique.
The full talk from Saban is about an hour long, and worth bookmarking for when you have some time.
https://youtu.be/ZZ-BwrRCm5k?t=1004