This is being caused by a default setting in Chromebooks that will need to be modified for courses to play properly. In order for videos to play, you will need to manually disable their "Hardware-accelerated video decode" setting.
Here are the steps to do so:
1) In a Chromebook browser, type the url "Chrome://flags"
2) Locate the setting "Hardware-accelerated video decode"
3) Within the "Hardware-accelerated video decode" click the word "Disable." Once this is complete, the word below the setting will change to "Enable" and you know the action has worked.
4) Restart the computer
5) Try watching a video within MedBridge