There are a few classes that are posted on Youtube or other sites (not via the official OCW channel) by instructors or students, like 6.004 and the Underactuated Robotics course.

I would argue 6.046 doesn't necessarily represent the bleeding edge of algorithms. For the most advanced/modern, there's the graduate-level course, 6.854: https://courses.csail.mit.edu/6.854/21/course_materials.html

(The 2021 videos are on Youtube, unlisted.)