I am deaf and I specifically remember about MIT OCW from a couple years ago that, whenever I found something that seemed interesting and had video lectures available, the lectures didn't even have a transcript, much less captions. I went to their website again and literally the first course I picked lacked captions,[1] unless you count the YouTube-generated "love with a system age to have an with a system" as captions. It wasn't very hard to find another seemingly interesting course that doesn't have captions either.[2] Admittedly, after further inspection, more courses seem to have captions than before.

[1]: http://ocw.mit.edu/resources/res-6-008-digital-signal-proces...

[2]: http://ocw.mit.edu/courses/physics/8-851-effective-field-the...