Each lecture comes with 2 24-hour viewing periods, which you may redeem at any time. For example, when you redeem 1 of the 2 viewing periods you have for each lecture, you will be given 24 hours to watch that online lecture. Similar to a movie rental from iTunes, during that 24-hour period of time, you may pause, stop, rewind or forward through the video as much as you would like. After that initial 24-hour period is up, you will still be able to watch the lecture again over a 2nd period of 24 hours whenever you redeem your 2nd viewing period, as long as your account is still active (i.e., 1 year from the date of purchase). Most people will watch each lecture once and then work on practice test questions in their Q-Bank before coming back to re-watch any desired lectures or content.