Video stops after number of seconds only in cell phone display

Try and narrow down the problem first.
Is it happening only with these videos or with others also. Have you tried using different video formats webm, mp4 etc.
Where are you pulling the video from, Qualtrics lib or somewhere else. Is it happening at all the places.
Have you tried the video of different resolutions, size etc.
Is it happening on a particular browser or with all of them. Is it happening on a particular mobile phone or have you tried others.
Are you using any custom settings such as auto advance or JS or timer or CSS etc. Is it happening without them also.
Have you tried creating a new question with just the videos? Is it happening over there also.
These will help identify the source of the problem and possibly point towards solution.

O.k, I'll try that first.
thank you.