Hi, Tesh speaking. I'm new here, so pardon me if I am handing out useless information. I tend to rant, so I highlighted the relevant information.
I've only had the game for about 50 days now, so I haven't played as DDD yet.
However, I saw this thread from the character boards screen and I love hearing about glitches.
Long story made short: I read the thread, watched the videos, turned on my wii and tried it.
No one here mentioned that you have do this very easily using the wii remote and nunchuck, it seems.
I tried it with the gamecube controller, I don't have a classic controller yet. Its a bit difficult. But with the wii remote and nunchuck, if you set the Dpad(Not sure what its called, the directional cross above the A button) to do smashes (or at least the left and right buttons), every time you press smash left or smash right, you will move in that direction slightly. So all you have to do is tap the direction you want to go in very quickly to do this. I tried it, it works, but I also agree that it might not be useful. Once you jump you go back to the normal very slow speed, so I guess its like jigglypuffs rollout, they can escape by just jumping.
As for rumble possibly causing this, maybe you are right, I couldn't get the tilting thing to work more than just one small step on wiimote/nunchuck. Maybe it is because the nunchuck does not rumble, the wiimote does. In any case, in a live match, I think the wild frantic tapping of the button might warn your opponent right?