Recently I've got a few interns to look after and mentor, so one of them asked for some advice on improving their system design skills.
So I gave a long monolog on digging through the layers of abstractions and being curious and genuinely understanding how things work. After it, I suggested them to read a "Designing Data-Intensive Applications" book and also prepared a shortlist of talks that can work as conversation starter or places from where you can start digging deeper.
Here is the list:

https://youtu.be/WE9c9AZe-DY
https://youtu.be/j6ow-UemzBc
https://youtu.be/1TIzPL4878Q
https://youtu.be/CZ3wIuvmHeM
https://youtu.be/I32hmY4diFY
https://youtu.be/hnpzNAPiC0E
https://youtu.be/y2j_TB3NsRc
https://youtu.be/t7iVCIYQbgk
https://youtu.be/IO4teCbHvZw
https://youtu.be/6w6E_B55p0E
https://youtu.be/B5NULPSiOGw
https://youtu.be/_M-oHxknfnI
https://youtu.be/lKXe3HUG2l4
https://youtu.be/r-TLSBdHe1A
https://youtu.be/fU9hR3kiOK0
https://youtu.be/lJ8ydIuPFeU
https://youtu.be/5ZjhNTM8XU8
https://youtu.be/9RMOc0SwRro
https://youtu.be/tM4YskS94b0
https://youtu.be/H0i_bXKwujQ
https://youtu.be/m64SWl9bfvk
https://youtu.be/cNICGEwmXLU
https://youtu.be/em9zLzM8O7c
https://youtu.be/ohvPnJYUW1E
https://youtu.be/HJIjTTHWYnE

Write in the comments: what else would you recommend or what talk you'd add to the list.