If I understand you correctly, yes, I have done this, and it works for nose down. It feels you're tilting the disc from parallel to the ground to almost perpendicular to the ground, exposing the top of the disc to someone who would be standing on the side of the teepad, and all of the rotation is in your forearm/wrist?
I believe it helps me get the nose down, and I think it helps my release line up more correctly. From this position, when my forearm swings out and my wrist uncurls, I find that the disc ends up parallel to the ground but with good nose down. I can see that my just going through the motions slowly without throwing. Until I saw that, I was afraid that I was introducing off-axis torque and not telegraphing the shot properly, but all the evidence seems to suggest that that's not happening. See this article to recognize the potential downfalls of not keeping things lined up properly: http://discgolfreview.com/resources/articles/telegraphing.shtml
I haven't heard of anyone else doing it, and I can't say for sure if it's a good thing. I only do it for hyzer or straight throws, for anny's I keep my wrist neutral (instead of bending it down like usual) and focus on getting more wrist extension, pretty much what was described in the Snap 2009 thread. I make sure not to do what you're talking about if I want to throw nose up, it's an easy way to get both shots without changing your throwing motion. I have no idea if I'm doing it all correctly, my memory of any discussion Blake had on the topic is foggy, but I struggle so much with getting nose down that I've pretty much decided to go with what works. If I had good snap, it might also take care of this problem. I can throw 400', sometimes 450', but I don't have very good focus at the rip, and it could be that I should be fixing that instead of angling my disc like this, I don't know.
Could you point me to some of the videos of the Pro's you were watching, I'd like to see if we're talking about the same thing...