Pre stretching routine before squatting

Skip to the 11 minute mark on this video to check out some groin and outside hip stretching before squatting.  He does the stretch on a box using bands. I just take my leg and stabilize it on the safety crossbars on a power rack and then lean my weight onto my leg.  This gives a good stretch on the groin and hip and allows you to open your legs wide while in the hole at the bottom of the squat.