This is a Feldenkrais Awareness Through Movement lesson.
See below for the summary. Enjoy the lesson. Thanks.
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Title: Lift a knee with elbows extended on all four

Unlike the title, this lesson is for rotation of the pelvis and the lumbar with the upper spine in extension.
You learn to extend the left and the right knee alternately while elbows extended.
Extending knees in this position requires rotation of the pelvis and the lumbar spine.
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Less: http://www.dailymotion.com/video/x6da8wu