This feature is currently unavailable on iPhones or iPads.
While on the Player page, move your mouse to the top right corner next to the video that is playing. This icon will display. Click to make it full screen view and hit "ESC" escape key to make it smaller again.
PLEASE NOTE: Do NOT click on the X next to the full screen icon or your video will disappear. To get it back, click on "Source" in the bottom right side of the player, and then "Video 1"