By threatening the cross choke opportunity opens up for the scissor sweep. The threat of submission from closed guard keeps you two steps ahead of your opponent because before they can address opening the guard, the choke has to be defended first.
Matt Darcy shows the traditional cross choke. Also incorporates the sling shot, clubbing the head and bypassing the hand defenses for a baseball bat style grip.
Matt Darcy shows a basic arm bar setup from closed guard adding the juji-gatame roll when your opponent uses the stacking defense.
Chris Fletcher shows the simple collar choke finish after taking the back from the turtle position using the knee scrape