After you enter your name and payment information - this screen will appear. You can click 'Download' - highlighted here.
This screen will pop up - click 'Download.'
This small arrow next to the web browser address bar will show the progress of your download. You don't have to wait for the download, it will happen, even if you move onto other things.
Once the download is complete - your video will be placed in your 'Files' Folder on your home screen.
Look for the file name, select the file to play your video anytime.