The learning process...
A lot of what we're talking about concerns the learning process. My understanding is that the more stimulus you use to teach, the better your students learn. In Aikido terms, that would mean learning a technique by hearing it described, seeing it done, and feeling it is better than just seeing it and then feeling it.
At the same time, I can see the point about being a mute uke -- especially when you're of low rank (like me). For a while, I was trying to explain things to nage when he ran into trouble, but now I tend to keep quieter. Part of the reason is that my sensei pointed out my tendancy to be a bit too vocal (hey, I'm a talkative guy and I'm enthusiastic about what I'm learning. It's hard not to talk about it or explain it to somebody who's struggling). Mostly, though, I'm realizing how much I don't know and that makes me a bit uncomfortable explaining things.
P.S. X-Men *was* great!