Changing button status "when timeline reaches"

On each of the video slides add a Cue Point to the timeline.

For each video slide create a T/F variable (for example, Video_1_Viewed) then create the trigger to change the variable to True when the timeline reaches your Cue Point.  Use a separate variable for each video slide.

On the Overview/Discovery slide, add a trigger to change the state of the button to Viewed (or whatever state you want) when the timeline for the slide starts.  Add a condition to the trigger:  if the Video_1_Viewed = True

Repeat this for each button on the Overview/Discovery slide.

Note:  The video slides allow learners to click the video to pause it, and click again to restart.  When the video is paused, the timeline continues.  The result is that learners may pause the video by clicking and the timeline will continue to run until it reaches your cue point.  This may bypass your intent to make the learner view the video to a certain point.

To prevent this, I inserted a rectangle over the top of the video and made it transparent.  A box with no fill will not work, it has to have a fill but be 100% transparent.  The timeline for the transparent box ends at the cue point.

Lastly, I disabled the back and next buttons to prevent learners from leaving the page until the cue point is reached.  Then they become enabled.  

You can see all the variables and how they are set up in the attached file.

Hey Garth, thank you so much for the quick answer and the template. I'm going to try that out right now but it makes sense to me! :)

Kind regards

Romea