Assuming you've seen the film through to the end, and that you're the curious sort, you're probably thinking about how the computer-generated effects were combined with the live footage, but what if I told you that EVERYTHING you just saw was computer-generated, EVERY LAST FRAME of it? What if I added that the entire effort was seen through by just a single individual? Granted, it seems to have taken this Alex Roman guy a year's worth of effort to put the whole thing together, but considering how long (and how much money) it took James Cameron to make "Avatar", one man spending one year to put together a short like this is truly an incredible feat.
Perhaps most impressive of all, though, and most indicative of the future, is that Alex Roman put it all together using commercially available, off-the-shelf software: Autodesk 3ds Max, V-Ray, Adobe After Effects and Adobe Premiere. Sure, the cost of these packages add up to several thousand dollars, but when you consider that a Canon 5D Mark II, a 24-70mm f/2.8 lens and a 70-200mm f/2.8 zoom cost even more, while even a "low-end" RED camera goes for $17,500, the expense associated with the 3D packages starts to seem like peanuts. It is clear that a new world of low-cost, high-quality film-making and special-effects is opening up, where you won't need a multi-million dollar budget to make a splash, just lots of talent, a compelling vision and a willingness to work hard to realize it (though in the end, these are the things which are always in shortest supply, aren't they?).
PS: For anyone tempted to say that this is a hoax, I suggest watching this video which gives a little insight into how the film was put together.