Uh, I don't know how you guys would take this, but I was trained to do that way.
Well, not U.S. Army though. I was in an infantry regiment of South Korean Army(R.O.K. Army). Not an SF unit or anything, BTW.
If you ask me why they taught us to run like that, I don't know. They didn't tell me about the whole "tactical" reason and stuff.
(We draft guys here so things kinda go around pretty differently here.)
All they showed me was that 'stance,' and how to quickly shift to other positions such as kneeling, and going prone.
Additionally, watch these two video clips.
1. "Act of Valor" -
http://www.youtube.com/watch?v=ZnlPgo9TaGo
As you all know, the characters of this film were portrayed by active duty Navy SEALs.
From 2:07 to 2:10, you can see the operator rapidly kneeling while holding his M4A1with one hand, pointing upward.
2. This one is a documentary film about South Korean(R.O.K.) Navy UDT/SEAL team and their training. (One of ours.) -
http://www.youtube.com/watch?v=s3FOn...eature=related
It is in Korean but language is not what really matters here. Anyway, watch from 42:40 to 43:05. There it is again.
Finally, I remember the devs saying all the character animation was done by motion capture which was shot with former U.S. Navy SEAL operatives so I think it's pretty awkward that some of us here are actually questioning the "authenticity" of it.