Mobile player is missing navigation elements for events with only one video

Steps to reproduce:
1. Upload a video with only a presenter or only a presentation video
2. Play the video using the mobile player
3. Try to activate the navigation by tapping

Actual Results:
The navigation UI is not visible for events with only one video. It is visible for events that have both a presentation and a presenter video.

Expected Results:
The navigation UI should become visible when tapping the screen

Workaround (if any):