After you purchase a video (or a PDF) you can download it from the “downloads” section on the “My Account” page.
Please download the video to your computer (and NOT to your smartphone) as the size of some of the files can go over 1GB.
Furthermore, some of the files are ZIP files (that should be unzipped after download).
Zip files can be unzipped by your computer OS or by apps like WinRAR.
For a video demonstration please click here
And here is an explanation using a screenshot: