In this one Scott Epstein a.k.a. "Einstein" demonstrates a really nice counter to the Darce choke from the labs at 10th Planet Jiu Jitsu Hollywood. This is a great technique.
The most important thing is to first arch your back in order to prevent your opponent from landing the choke. This principle is Brazilian Jiu Jitsu 101. Protect ya neck !
When you arch your back your opponent's arm is right there for the taking. This sweep is most effective I have found when you have the Lockdown on your opponent's leg. If they pass the guard it may still be possible to land the sweep if you maintain control or your opponent's wrist. Click Here to see the vid.