The way I view the videos is to rt click on the video and open it in a new window. If it didn't work, I just went on to the next one, and so on, but it might take about four videos before I got one to work. Never went back in the same session to retry one. So the next time I watched the first and noticed that he rewards points weren't showing, so I paused it, closed the window and then reopened the same video again, in a new window and it worked, and so did the rest of the videos.
Every day I have to reload the first video that I attempt (sometimes more than once) until the red message "AARP Rewards: Why it matters" displays. Also, the 300 point AARP Reward circular button appears behind the message. Even if it displays the message on the first try, I still reload the first video and check make sure that I got points for it after completion.
Of course, it may be different for each user/browser/astrological sign/etc.