That's because the staff needs a schedule similar to the academic schedule so they can answer questions, correct things, participate in the forum discussions...

That's because the staff needs a schedule similar to the academic schedule so they can answer questions, correct things, participate in the forum discussions... Crypto I has been offered several times though (at least 4 or 5). If you ever signed up for one of the offerings, you can still access to the full course (videos, lectures, and I think even the automated grader) as well as the forums (but the forum activity usually fades down after the end of the course).