demonstration of floating from seated to chaturanga.
In this video Jason Schramm of Detroit Yoga - Ann Arbor, demonstrates floating from seated postures in Ashtanga Vinyasa Yoga. You can see that it is not the length of arms that matters so much as causing the hips to rise up, which takes the legs through in the process. Persistence and hard work are what is needed...not long arms.
Here you'll find demonstrations and tutorials going over postures, movements, and details of Ashtanga and Vinyasa practice.