I shot a video clip on my iPhone 5 and emailed it to my mom. She can't open the video on her iMac, her iPad3, or her iPhone5. What is going on?

I have the latest software update. Mom has the latest software updates. She cannot open this video on any of her Apple devices. She has iPad3, iPhone 5, Imac. I cannot think of any reason that she can't open them. My wife can open the video on her iPhone 5, without problem. I texted and emailed the video. Is there something in the settings? Thanks, in advance.