You can add videos in MP4 file format to CoverageBook. If you have any problems, pease check the file name doesn't have any spaces, full stops (or periods) or characters like # symbols in it.
If it does, try renaming the file to something simple without any additional characters (- and _ symbols should be fine).
If this doesn't work the file may need to be converted to the right format. our guide on this is here
If you are still having problems after this please contact email@example.com with a link to the report and details of the MP4 file.