The page "Header Image" field populates the header background image.  If a header video is present this image will be the preview image while the video is loading and also serves as the fallback for devices that do not support video.

Images should be 2,732px wide by 1,340px tall.  If the header text field is used for the page the image size may need to increase in height and depend on how much content you place in that field.  

If the page "Header Overlay" field is checked the header area will display the site dark overlay option.

Using the field "Header Background Video (mp4/h264)" will replace the background image with a background video.  The video must be MP4/H264 formatted video and should have a ratio of 16:9.

*NOTE - This is a looping/muted background video so the video should be kept short in size/length (under 30 seconds).

If a rotator is assigned to a page the images will display as slides.  The title and caption or optional and will display as an overlay.   The button uses the Button Text field.

Note - There is a "Slide Overlay" checkbox that will allow you to assign the dark overlay option to specific rotator slides.