- Many convention talks are really good and are too many to list
- OWASP
- zseano
- hackerone
- Bugcrowd (Jason Haddix's stuff is a pretty important pillar)
- OWASP
- DarkOperator
- Absolute AppSec
- KacperSzureEN
- PwnFunction
- LiveOverflow
There are a ton more, these are just ones I've been watching in the past 6 months or so.
'IppSec' has around 100 CTF walkthroughs.
'Open SecurityTraining' has ~200 tutorial vids on topics like reverse engineering and malware analysis.
Edit: added a few more.