Please help! slide layer finishes before activity is completed

Sarah,

Having worked with JudyNollet​ and some of her ideas, she normally has some good ones. I think this case Storyline will not do what you want. To stop the timeline there needs to be either a trigger or a button to control it Stop/Start. 

So, with that in mind you could extend your timeline and put a trigger that stops it about a second after the main part is done. I would put a mask over the 2 videos so the learner can't click on them until the main timeline is finished, also a trigger that removes to mask. 

Now your learner can click on either layer can play, again I would add control to stop/play/rewind the video. Extend you timeline and pause the timeline so they can answer the check boxes. At this point everything will sit. They can review their answers, stop for a phone call, or do whatever. 

Now we need a trigger to restart the timeline, some type of action. This needs to be some type of trigger that will only appear when your box conditions are met. The same would need to be set for the other layer. You could add buttons to replay the videos if you wanted or go back and reset the layer to original and clear the boxes. 

I don't work with screen readers so I'm not sure what they can do and what they can't. But I don't think Storyline will do what you want without buttons and triggers.

You may need to move the layers to 2 separate slides and let the learner see 1 anser the questions, then move to the next. Or Lighthouse boxes may work also. 

Good luck, reach out anytime and I'll see if I can help.