Asking on behalf of an instructor who teaches with the assumption that students have adequate bandwidth to participate in their online sign language course...

The instructor relies on the RCE video upload capability quite heavily for assessment in quizzes, and always has at least one or two students say they cannot get it to work. Since they are mainly assessments, the students don't typically know the prompts they are supposed to record ahead of time, and uploading files is out of the question. They need to record on demand when prompted.

I know the answer is the higher the better, but what bandwidth number for upload speed would you say the instructor needs to tell their students when they are starting the course to expect to have on hand in order to get an adequate learning experience when recording on demand?