Important detail! Pay attention to how Master Carlos prevents the opponent from scrambling to their knees (and possibly taking the back) by pulling upwards on the sleeve grip and beating the opponent to the underhook.
The takeaway: A strong upright posture and solid, low base is of paramount importance in the closed guard top. The guard player has many sweep and submission options and your best defense is a strong posture on top.
See also on GB Online:
Butterfly Sweep Grip with Prof. Flavio Almeida
Writer: Mark Mullen, Gracie Barra Black Belt