http://mirror.as35701.net/video.fosdem.org/2016/ All the fosdem videos

Great insights about API design and implementation in general. The title makes it sound specific and technical while the subject matter concerns pretty much every developer, I recommend you watch it even if you're not interested in low-level programming.

YouTube mirror: https://www.youtube.com/watch?v=DOZZOLHQpd0

It's amazing how you can deliver world most used software without unit testing.