I never rate previews highly
Firstly, it's obvious that those backdrops weren't done by computer because of the lesser quality drawing of the ninja. Not that that's a bad thing, it just makes it a while lot bigger and longer to load. 3MB for a trailer? That's a bit over the top.
The main body of that was just a tweened movie clip. With no real animation except for at the end. If that's a preview, I'm guessing the proper episodes will be at least 10 times as long. And I'm not willing to sit through 20MB of loading to watch another lengthened version of that.