Web based elearning with multiple mandatory videos

Hi All,

I'm building courses that are multiple videos and I really need some help. 

I want learners to not have the ability to fastforward on first watch- or be able to hit the next button. (Idea is they won't receive course credit unless they have watched all videos) 

But once course is complete I want learners to have the ability to fastforward and hit the next button. ( Idea is they can come back to the course for a refresh on the videos at a later date without watching the whole thing)

I currently add a transparent shape over my video seekbar- with a trigger to make it hidden after video completion

I set the state of next button to disabled when timeline starts

Change state of next button to normal when media completes.

However if learners return at a later date the next button is disabled on all videos.

I've tried to add a T/F variable to each slide ( see attached) but it isnt' working 

How do I make the next button normal when the course is complete if the learner returns at a later date?