If the video is stopping or moving slowly, it could be that the video is loading on a slower internet connection. Pause the video until it loads, and play once loaded.
If the video screen is blank please contact firstname.lastname@example.org. A blank screen can occur for a number of reasons, and we may have to involve our internal IT department to resolve the issue. When submitting your request, please be sure to include a screenshot of the blank page, and a detailed description of the incident.