Stay on me with this if you really want to see a video, but the one we use most (depending on the angle of attack and the style of Darce Choke… not all Darce Chokes are created equal), is to put your arm that is encircled by your opponent between your legs.  This takes your shoulder off your neck and allows you to keep blood pressure going to your brain on at least one side of your neck.

That isn't to say you won't tap from the pain and pressure of his forearm on the other side.  But it is pretty effective in terms of defending against the Choke.

Other possibilities are pre-emptive measures can be seen in a few of our previous videos seen below.