.mp4 video files won't play on quicktime from WD My Cloud Desktop App

I have a Macbook running OS X Yosemite 10.10.1. I downloaded the WD My Cloud Desktop App to connect to my parent’s my cloud. When I try to open and play a .mp4 video file, Quicktime opens but it can’t find the video file to play. Generally, it ends up saying “Application Not Responding” and I have to force quit. 

While at my parent’s house, I could play the videos perfectly fine because I could see the cloud on the network and not use the WD My Cloud desktop app. 

Any help/suggestions would be appreciated.

Hello ppetersen, welcome to the WD Community. Have you tried to download the .mp4 files first? 

What is the Internet upload speed where the mycloud is? measured with somthing like speedtest.net