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 mobile devices.

If the Header Text wysiwyg field is used it will display as an overlay and replace the page title.

Page Header Images:  1,350px wide by 458px tall.  

Page Header Images w/Header Text or Background Video and Rotator Slide Images: 1,350px wide by 768px tall.  

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.

Title Image URL uses a full url path to an image.  If this field is used the title field is typically left blank.