about the stretch in the first video (below).
1. It is best to hold onto something. Taking out the balance component allows you to concentrate on releasing the quad muscle. Also, to balance requires a little tension in some alternate muscle groups, so you may not get the desired level of stretch.
2. As you hold the heel to your buttock, try to feel the leg release from the inside (your femur, or thigh bone) to the surface of your skin. This simple idea allows you to get much deeper stretch sensation.
3. Make sure your hips are level.
5. Breath. It helps to relax no matter what, especially when you are trying to stretch a muscle.
6. Try this: After doing both legs, and rolling your hips as shown, repeat the exercise. You will be rewarded with much greater stretch than you started with.