This is my first post on Macrumors but i would just like to say i think this video is real. and i also think apple had something to do with it getting posted, and here's why:
1. The videos are everywhere. I find it hard to believe apple would let everyone show them if they didnt think the showing served a purpose. this brings me to point 2
2. Assuming this is real, these videos really help apple. They soften the ground for releasing the tablet the way it is. meaning people wont be shocked when they see it for the first time, as not only have they seen the concept of iphone apps running in small windows inside the tablet, they also have had time to
like it. Most of the backlash to such an idea has been already
posted as response to this so-called fake video, and now there is more room for the
complements that come later (notice how Gizmodo, in a very short period of time, has already gone through both phases).
3. On one hand, people wont be surprised as to the general concept of the tablet, but on the other hand they wont be bored. these videos reveal the concept but very little else. the reason they are so short is that it leaves much to the imagination. Also, the OS in the video is obviously unfinished, leaving the "wow" factor for the announcement of the final finished version.
All these points are assuming this is real, which i do assume because the pictures/videos seem so tailored to apple's needs.