You're not the only one. If this is real, they seem to have gone out of their way with editing to make it look like a fakery. I would have been far, far more convinced by simple, unedited HD footage. For what it's worth, a friend of mine who is a Boeing engineer saw it and cried "fake." I think I need more information.
If this is an attempt at viral marketing, it's worth remembering how many people got pissed at the shoe company that commissioned the Liquid Mountaineering ad - Hi-Tec I think it was.
Edit: If you watch his previous video, at 1:53 here you can clearly see the leaves changing as it blurs and cuts to another shot. http://www.youtube.com/watch?v=Q0tKFOcHyrI&t=1m50s Debating this is a waste of time, it's another hoax.
Liquid Mountaineering looks to be the exact opposite of this.
That was clearly a platform just under the surface of the water. The actual footage was genuine, they just weren't doing what they claimed to be doing, whereas this certainly looks to be a total fake job.
It's oh so convenient that the cameraman "happens" to look down and the camera happens to blur (what is it refocusing on?) between the time when the wings are resting on the ground and when they are picked up and ready for the test flight. Then the camera is conveniently moving and keeping things just a tad blurry while the wings start up. If you compare the appearance of the wings before and after the cut you'll notice some slight differences.
Definitely fake as there is a black square on the right wing in the later (CGI, after the camera has looked up again) images that doesn't exist in the earlier (real) footage. You can clearly see this in the video and your screengrab.
From the video it is also obvious that there is no way someone could have stuck that there in the time it took for the camera to turn away and back again.
I'll also go on record here calling shenanigans. There are a lot of things that look mighty fishy about that video. I hate to rain on the parade, but I'll be surprised if it turns out to be legit.
Which parts seemed to be cgi? There was edited footage, but it doesn't seem wrong. I don't know why someone would go through all that trouble with the other 14 videos to create 1 fake one.
Have you ever tried to video kids trying to launch a kite or a glider?
They really do act just like that. The camera person stops to video and everybody runs in front of him. The camera person needs to change position quickly so you tape the grass whirling for a few seconds.