War story time:

I can't watch your video(no youtube at work), but I do wanna tell a story of when I first met my match!
So no @#$%, there I was.. 3 elemental shamans level 58 in the 51-60 AV. I was knocking the 60 twinks down to 10% with my first chain lightning, so I was feeling pretty good. Every 6 seconds someone would die from chain lightning, and in between others would die from fast LBs or shocks.
And then 6 moonkins came over the hill, and dropped an entire forest on me.
Fighting 15 treants would maybe have been manageable, but that doesn't account for the 5v3 wrath and moonfire spam that was coming in. I lasted 4 seconds!
so I do think balance druids have their place in multiboxing. It's more of a challenge, and definitely something different, but I think it's worth it.