You've probably seen the Most Ridiculously Photogenic Jiu-Jitsu guy memes. Clark Gracie has only recently become more of house hold name due to him winning his first world title at the 2013 Pan Jiu-Jitsu Championships. Clark Gracie won in epic fashion against Marcelo Mafra that saw him come from behind and choke him out in the final seconds to claim his first gold at the highest level in his career. Clark Gracie's "meme fame" came about as a result and the very match this photo was lifted actually took place at the IBJJF New York Open in 2012 (before the Pan match).
Commentary (Skip to the bottom for the video):
This match would start in typical fashion. Ken Primola with his wrestling background obliges Clark Gracie's open guard pull. Both fighters waste no time establishing grips. Ken tries to pass low on the knees but Clark is able to keep his grips and invert preventing the pass.
Clark manages to set up his spider guard with leg lasso. At the 1:00 mark Clark removes his right hook that was used to prevent Ken from passing, then inverts underneath him for the omoplata. Because Ken is standing it is imperative that Clark sucks his arm in and shoot his hips high to secure the omoplata shoulder lock position on his standing opponent.
Ken steps over to the far side but his shoulder is still trapped. Ken attempts to drive his near side knee into Clark to help him posture but it's no use. Clark manages to secure his left arm over Ken's back.
Ken stands and Clark maintains a grip in the collar and one on the leg to disturb his base. Clark alternates his grips in an attempt to make him come back to the ground. It's worth noting that once he brings Ken lower, Clark lets go of the collar and focuses more on the legs. When Ken begins to posture back up Clark attacks at the collar again to disturb his posture.
At 2:20 Ken finally has to set him back down out of frustration. Clark does an excellent job to move his hips away from Ken to keep him broken down. At 2:26 Clark uses his far hand to attack the collar and begin setting up his choke. Clark begins sitting up and Ken chooses to roll which is exactly what Clark wanted.
Link for mobile users: http://www.youtube.com/watch?v=TYfOZ8VNI4M
For more awesome references to omoplata setups, take some time and watch this episode of Budovideos Rolled Up with Shawn Williams. Shawn is a big fan of the omoplata and goes in depth with the position. Around the 4:18 mark Shawn does cover the omoplata choke and details to finish it. Give it a look.
Link for mobile users: http://www.youtube.com/watch?v=zoyzLVDV2HM