Tracking when a video has ended

Hello all, 

I have a video on a slide that, when finished, makes a hidden next arrow and final instruction visible and available.

However, we have now been asked to add the control bar to the video meaning the user can scrub the timeline and jump ahead.

This breaks the trigger to reveal the hidden bits as Storyline does not seem to now know when the timeline for the video has finished.

Obviously I know the length of the video so thought I could put the hidden elements to appear with a secs or cuepoint count instead.

But again if the learner scrubs to the end, they then have to sit and wait for the slide's timeline to reach the right amount of secs or cuepoint.

Any tips on knowing whereabouts  a video is along its own timeline?

Thanks!