Hi Michael,
This is a relatively common issue, and here are the most common reasons why this can happen...
- The download is incomplete. Often this happens due to an unstable / slow connection and can be fixed by going to a faster network.
- The program you are using to extract the files is not able to do it correctly for some reason. My recommendation for this would be try to another unzipping program such as 7-zip, winzip, winrar or the default windows extractor. Since it looks like your download is complete I would believe this would be the best solution for you.
- An anti-virus / anti-malware is corrupting the file as / after you download it. This is happens less often than the first two reasons but you should still be aware of it. If neither of the solutions for 1 or 2 work then I would recommend turning off your anti-virus and trying the download again.
Another common solution that a lot of people will do is to download the DVD on another computer that is preferably on another network. Once the download finished, use the other computer to extract the files and then use a flash drive to move the folder back. This will bypass all three of the above problems and if it is an option for you, will probably be easiest.
Please let me know if the problem persists! Thanks!