I think the video is authentic because of how it looks and what Gizmodo has been reporting on.
It doesn't show a lot of details that really matter but enough to show that there is a frontal camera and that we're very close to seeing it for real in June.
The key questions still aren't answered by the video: if Verizon will get it, when we'll see it, and other juicy stuff. Only Steve Jobs knows for sure at this point.
The video and more at On Apple.