Actually what Maude said is not totally true. You can watch the game from any time. Just click on the button the time bar at the bottom of the screen. Drag to the far left to start at the beginning.
GCL defaults to Live
I just did it now on the Rangers/Jets game and it went back to the beginning,
See where it says, 1:04:06. Click and drag that circle to the far left. It will go to the beginning.
Unfortunately, I am getting the same results - only being able to go back a few minutes. Now I am using it on my Android TV box, not my computer. I wonder if it lacks some functionality on Android than it does on Windows.