When I open up the YAML template, and right click to save/download, it will only give me the options of ‘Page Source’ or Web Archive’ as the format to download to, not YAML as instructed in the video.
Select RAW format on Github and copy the contents of the template. Next, open notepad and paste the contents. Save the notepad file as "acg-dynamodb-template.yaml". Make sure you change the "Save as type" drop-down list in notepad to "All Files". Then save the file to your computer. That will create the .yaml file for you on your computer.