Yeah, I'm sorta new here, so I didn't know a thread was already made. But, I'll try the shield-drop, roll, backflip method and see if it works. I think I have the TIMING down, just not the difference from the bomb. Also, I didn't expect you to watch the ENTIRE thing, just enough to see what I was doing wrong xD
I think your timing is off because your distance is off. You're too far away from the bomb, so you end up rolling early. Get closer to the bomb and roll later. Link getting hit by the explosion is OK (it shouldn't damage him). Check this out:
http://www.youtube.com/watch?v=VfO8gOnuAqINotice how Link doesn't roll until right when the bomb explodes (not before) and how right before backflipping you can see Link getting hit a little by the explosion. You should be able to hear him make a noise in between the roll and backflip.
The spacing isn't very precise, there's a lot of wiggle room. Just get closer and roll later.