This is most common issue for iPad device.
What you can do is login using a computer to view and download the files instead of playing the videos using your iPad.
The iPad doesn't support flash video players natively so what you'll see is a white area.
Also the iPad doesn't support zip files natively so when you click to download the materials you'd need to use an app like izip
to uncompress the files.
I hope this helps.
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