Isn't every lecture, on-line or off, unavailable to deaf students? How does it work in legacy education? Is there a sign language interpreter in every hall?
At my school, they did indeed put an interpreter in any class with deaf kids (we had a lot of deaf students). The school would also pay hearing students for their course notes for distribution to deaf students, so if you were deaf and felt like sleeping in, no worries you'll get the notes anyway.