Note: MP4s are in a digital downloadable file format. You can watch your downloaded MP4s on your computer or an MP4 player but unlike DVDs, you will not receive a physical DVD. Remember that videos are available for download for a limited 72-hour period after purchase and may be downloaded only 5 times. Be aware that the file size may reach up to 10GB and the download time may take several hours.
Note to iOS users: In order to download and save MP4s to your mobile device and to avoid streaming them directly in your browser, you will first have to download the file to your computer. Then connect your iOS device to your computer and copy it over using iTunes. See this support topic from Apple: iTunes: Frequently asked questions about viewing and syncing videos.