Okay. I have to try and restrain myself here, because this could get really long really fast.
But you have to be real careful saying that there are definitely "other universes". First, keep in mind that the guy in this video (Michio Kaku, a physicist at NYU, I think) is a theoretician. What that means is that even though he mentions experimental evidence, 90% of the things he says are basically speculative, only based on some equations on a piece of paper. It's an intriguing and mathematically simple solution to have other universes, but there's really no concrete, empirical evidence for the idea itself as of now.
Think about it for a second. If there are really universes outside our own, how would we know it? By definition, they're completely separate from ours. It's an interesting possibility, but only one of many.
Sadly, that goes for most of the things Kaku says. Keep in mind, he's trying to sell books and stuff to the public. Claims like that are what grabs people's intention, but in most cases their experimental verifiability (at least with present technology) is dubious at best. I've read several of his books at least partially, and even though they're interesting, most of what he says is still very theoretical.
Don't get me wrong, this stuff is incredibly interesting. But there is a lot more to it than this 10 minute clip. It's great that this is getting people interested in science, but there is a line where it ceases to be science and becomes science fiction, and in my opinion Kaku comes pretty close to this at times. And trust me, there is a lot of proven science that is just as interesting - someone earlier mentioned quantum mechanics, which is interesting and has been experimentally verified to amazing accuracy.
Sorry, that ended up pretty long, but whatever. This is my area of interest - I could go on a lot longer.
Sparknotes (this one needs it): Interesting movie, but all very theoretical.