If a student views a video lesson part way, leaves the lesson, and then returns to the lesson at a later time, they will be able to automatically continue from where they left off!
Note that this only applies if the student is viewing the course on the same device, as these details are cached within the browser. This means if they start a video on their computer and then return to the course on their mobile phone, it will not start from where they had left off. We don't usually find this is an issue as many students use the same device when working through courses.
This functionality is not available within the Legacy Course Player. For improvements to your students' experience and other features, see how to update your Course Player here.