I've selected multiple video formats in the Video block, which file will be used?
The add-on first checks if there is an MP4 file. If not, it checks for a WebM file. Finally it will check for an OGG file. For that reason, make sure you modify the file attributes of the 'most important' files.
How can I modify the title or description in the structured data?
Go to the File Manager, right click on a file and hit 'Properties'. There you can modify the title and description of the video.
How can I add a 'duration' property to the structured data?
Go to the File Manager, right click on a file and hit 'Properties'. Then you can change the duration. Please add the value in seconds. It will automatically be changed to the ISO 8601 format.
Where can I verify if it works OK?
Go to the Testing tool: https://search.google.com/structured-data/testing-tool
Why is concrete5 8.5.0+ required to add video information to the sitemap.xml?
Because there were some bugs in how the sitemap events were handled. Those bugs have been resolved in 8.5.0. To see it in action, you can view this sitemap: https://a3020.com/sitemap.xml (you may want to search for 'video').
Where can I read more about video sitemaps?