If it's the same one I'm thinking of, it's this one
http://www.youtube.com/watch?v=KBm_ODQ91Zc
Anyway, I learned a Secret Technique this weekend, from Koto (aka Thunders). It's a guaranteed edgeguard against Peach's umbrella from below the ledge, but it's a little hard to do. Anyway, you grab the ledge, and you know how Peach can kind of float there for a bit and make it really hard to edgeguard the umbrella from below? Especially since it blocks you from shine spiking her or hitting her.
So you grab the ledge, but before you grab it, lightly hold R and toward the stage. Wait until Peach uses the umbrella, and as soon as you see it, hit L (all the way down). You will ledge tech; immediately shine her. Obviously L and R are interchangeable.
You lightly hold R so that, when you hit L, you don't roll up the ledge.
Thought I'd share it on the fox boards cuz I thought it was pretty cool lol.
The more fundamental thing I learned this weekend, is that, when fighting Peach on FD (which I do a lot these days), THE most important thing in the matchup is to DI her dash attack away. If you do that, the best she can get out of a dash attack is another dash attack, then she's done. If you don't DI the dash attack away, she gets a grab, which is always death. I mean, yeah, common sense right? DI the combo move away. But it's Peach's easiest way to get a grab vs. Fox so it's worth noting.