I have to say when I watched the Secret my immediate reactions was...
Something's missing here.
It was too simplistic and glossed over the actual process of what happens when you use LOA. I'm an LoA proponent and use it consciously a lot. My experience of it's positive effects is certainly a hell of a lot different to thinking about an elephant and one shits in my living room.
For me it happens like this. I set an intention to create something then I find the quickest avenue for achieving that presents itself to me. I get the ideas and they turn out to be gems often producing far better results than if I just went about things half-assed. If you're not an LoA believer you'd probably explain it in terms of me being more mentally focused on my goal and therefore bringing my full intelligence to the problem ultimately coming up with the best solution.
I do find if I'm scattered or confused the results of my actions are pretty much hit and miss. If I focus through LoA I can take less action and get better results.