Answers to common questions. If yours isn't here, send a message with the form.
An MP4, MOV or WebM file, up to 2 GB and 2 hours long, with both picture and sound. Any resolution is accepted. Lectures play back at up to 720p, so a 1080p or 4K upload is converted down; exporting at 720p before you upload makes processing much faster.
The upload itself depends on your connection. After that, a one-hour lecture is usually ready in 3 to 10 minutes: about 3 minutes if the file is already 720p or smaller, longer for 1080p. You can close the page while it works, and you get an email when the lecture is ready.
Open the course page and press Retry on that lecture: it carries on from where it stopped. A lecture longer than about two hours can pause partway with a message asking you to retry in an hour. If Retry doesn't help, send a message with the form on this page and say which lecture it is.
Professors. Sign in, open Professor access and send a short request. Once it is approved you can create courses and upload to them.
20 a day in each course without signing in, and 200 a day once you are signed in.
Answers are written only from what is said in the course's lectures. When nothing in them answers your question, you get that reply instead of a guess. Try wording it the way the lecturer would, or ask about a narrower point.
Citations. Each one, like L4 · 31:32, names the lecture and the moment a sentence comes from. Click it and the video jumps there, so you can check the answer against what was actually said.
They are written by an AI model from the lecture and checked by a second pass, but some can still be wrong, especially in maths-heavy lectures. Use the report link under a question if one looks wrong; the professor can correct or remove it.
Give it a minute and check your spam folder. Each link works once and expires after an hour, so ask for a new one rather than reusing an old email. If it still doesn't come, send a message with the form on this page, from any address you can read.
Open the course and expand Manage this course at the bottom of the page. Only the course's professor sees it. Deleting removes the video and everything students asked about it, and can't be undone.
Send a message and you'll get a reply by email.