Why can't MP4 or M4V video formats be previewed in LabAuthor?

Previewing MP4 and M4V video formats is not currently supported in LabAuthor (part of the LabTutor 4 Teaching Suite). MP4 or M4V video formats will not play until the LabTutor Experiment is installed on a LabTutor Server. Videos will function correctly once the experiment has been installed to LabTutor Server, and are being accessed by logged-in students. We recommend you check videos outside of LabAuthor (before importing) to ensure the content is as desired.