Videos not playing
I found a solution for this a few weeks ago somewhere and it worked for me. I realized the videos don't play on the VM because of the audio settings (and not any video settings).
- Shut down the VM (in my case Ubuntu 16.04.1).
- In VirtualBox, click "Settings".
- Go to the "Audio" section and change the "Audio Controller" from the default to the other available option ("Intel HD Audio" controller was my 2nd option).
- Start the Virtual Machine and see if this work.