Video Controls. Enable and Disable

Here's an alternate version of Elizabeth's option that doesn't require two copies of the video. It does use a layer and a "VideoViewed" T/F variable.

Put the video on the base with the controls.

Create a layer. Leave it blank, except for a shape that covers the video controls on the base. Here's the important part: set the Slide Layer Properties to prevent the user from clicking on the other layers. That will prevent them from using the video controls on the base.

On the base, add a trigger that shows the layer when the timeline starts on the slide with the condition that the "VideoViewed" variable = False. 

Also add a trigger that hides the layer when the media completes (that is, when the video ends). 

And add a trigger that changes the variable to True when the media completes.