Splatfrog is a website with hours of lecture/demo videos by veteran animator, Ken Fountain. It has both free and paid videos.
Thinking Animation has a great section on the pros and cons of different rigs. As well as a bunch of other resources and tips across the site.
Kenny Roy is a 16 year veteran of the animation industry, and 7 year Mentor from Animation Mentor. Sign up to his members section for Monthly Videos, In-Depth Articles and more!
Quickposes is a tool for art students, illustrators or anyone who wants to focus on improving their drawing skills. By practicing gesture drawing you will not only get better at recognizing certain aspects of poses, but you will also build a visual library of characters and models.
Animator Island is a treasure trove of animation secrets, techniques, tips, and information on your quest to become a Master Animator
Line of Action is a really useful site for learning about the human form, anatomy, speed drawing and more. Useful for both 3D and traditional animators!
Animation Exchange was an 8 hour twitch stream hosted by a bunch of lovely animation veterans. The aim was to take the knowledge sharing and powerful community of art and development conferences and make it accessible to all, and it was awesome!
Alejandro Garcia has a huge Youtube video series all about physics in animation, covering topics like forces, weight shift, jumping and more!
12 Principles of Animation – Alan Becker has made a video series highlighting each of the 12 Principles of Animation as described by Frank Thomas and Ollie Johnston in their book “The Illusion of Life”