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NOBODY WATCH THIS!! THIS IS COMPLETE AND UTTER CRAP!!

It's not even about string theory. As for its merits on it's own:

As soon as it mentions the ant: Bullshit.
Multitude of paths: Bullshit.
"Quantum theory tells us": Copenhagen Interpretation
Collapsing probabilities from the fifth dimension: So that's where that guy got that hare-brained idea about the fifth dimension being probability.

Oh ********. It's started talking about infinity as the end of the universe. I can't listen anymore. It's this kind of pseudo-scientific bullshit that is makes me feel that the fight against ID is futile. If a hard field like physics can't stop cranks and jargon-spewers like this guy from convincing people of absolutely misguided s**t, how could a field as vulnerable as biology possibly withstand ID?

Okay, perhaps I shouldn't have sworn so much. However, as a math/physics major who has taken classes on both QM and GTR, I found that video to be horribly, horribly...misguided I guess would be the word.
The video makes it terribly clear that the author of that book has no actual knowledge about either string theory or mathematics.

First off, string theory postulates multiple spatial dimensions. None of this probability/possibility crap (bullshit, nonsense, inanity, take your pick). String theory says nothing about multiple universes. Some interpretations postulate multiple universes but travel between them is impossible.

Secondly, the third dimension should not be thought of as "folding the universe" or however he described it. That's called a non-Euclidean metric, which is a very, very different phenomenon. Most such foldings/warpings/whatever cannot be embedded in Euclidean space, and so he should not imply that they can be.

Thirdly, this whole bit about bending spacetime backwards is, in my personal opinion as a college sophomore majoring, as I mentioned, in mathematics and physics with an eye toward General Relativity and TOEs, on par with ID in terms of sheer lack of understanding.

Fourthly, infinity as the seventh dimension and/or the end of the universe. Don't get me started on this, as it is possibly the most intellectually offensive thing I have ever heard, even with ID, Neo-Platonism, and the whole "Ignorance is bliss" phrase.

Once again, I apologize for the swearing. It's a bad habit of mine to swear when I find pseudo-science of this caliber, and I know that I shouldn't do it. But the sentiment is there: this is the worst piece of drivel I have seen since the Evolution Crusher website, and I hope you take it with enough salt to kill a small country.

For higher dimensions, try something from Rudy Rucker, or Clifford C. Pickover; I remember liking them and from what I remember, they weren't too bullshitty. Pickover was more entertainment than science, if I recall, but you won't be led astray. They were how I first got into higher-dimensional/n-dimensional geometry and physics.
For a more intuitive view, try Flatland by Edwin Abbott and and Flatterland by Ian Stewart.

For string theory, try Lisa Randall's book Warped Passages. Well, first bone up on differential geometry, GTR and QM, but then try Lisa Randall's book. I didn't read the entire thing, but the first parts were pretty good, even considering the fact that I don't like string theory.
My personal favorite is, at the moment, Roger Penroses' Road to Reality. The pretentious title aside, it really is a good book, in that it builds up the mathematics needed to really understand GTR, QM, and the various TOE attempts. It is biased against string theory and explains why, and is perhaps the reason I'm also against string theory now.