To add your video first make sure that you have create it in a GIF format. If you have a .MOV or MP4 file we recommend converting it to a GIF use a free movie to GIF converter like GIFSKY.
Once you have your GIF:
Click on the 'Edit Header Section' to open the modal and scroll to the image.
Hover of the image to reveal the 'Replace' button, click it and then click 'Upload from Computer' to locate your GIF and insert it.
That's it! You now have a video playing in your header!