The Game Developer's Conference (GDC) is amazing. I went for the first time in 2015. It was super inspiring. And most of their sessions are recorded, and many can be accessed for free at the GDC Vault.
Here are some of my favorites!
Will Wright - Metaphysics of Game Design
Will Wright - What's next in game design?
Will Wright - Dynamics for Designers
Will Wright - Classic Games Postmortem - Raid on Bungeling Bay
Joel Burgess - Level Design in Open World Games
Stone Librande - One Page Game Designs
Stone Librande - 15 Games in 15 Years
Stone Librande - Game Design < Design
Zach Wilson - 50 questions to ask yourself when your level sucks
Eitan Glinert - Rapid, Iterative Prototyping Best Practices
Simon Darveua - Prototype: A Developers Best Friend!
Robin Hunicke - Deliberately Developmental Leadership
Tom Francis - How reviewing games for nine years helped in designing Gunpoint
Tom Francis - Efficiency for Game Designers - Lessons learned from making Gunpoint quickly without going mad
Fang - A live art demonstration of creating world through design thinking