Corey Lewis demonstrates a nice overhead squat. Our overhead movements develop shoulder and core stability. Notice some of the components to being solid overhead. The elbows are locked. A locked joint is a strong joint. It will stabilize heavy loads. Try bench pressing or shoulder pressing a maximal weight. Notice when you get it locked out it feels stable. Then bend your elbows and notice how much harder it is to hold. Keep your eyes staight ahead. You want to hold posture in the cervial and thoracic area as much as your lumbar region. Keep your shoulders solid but don't "shrug" up. This actually disconnects shoulder anatomy. When dealing with the overhead squat you need to make sure weight is evenly distributed across the foot. This applies to the toe/heel relationship as well as the instep/outstep of the feet. Knees should track within or slightly out from the line created with your toe and hip. Also, don't be afraid to let those knees travel in front of the toes. This should not be excessive and ankle flexibility or lack of will alter this movement. It is a perfectly natural position and it allows the hips to stay under the midline and under the weight.
The 2009 CrossFit Games website posted a couple more videos from the Team Affiliate Competition. Look closely and you will see our athletes in action.