The video is 15 seconds long and only plays when you click the play button, which is thankful, since the video was kind of stupid. You can change the volume. While the video is playing, moving your mouse over it showed that it was clickable, and showed an overlay with a URL.
Google has done a perfect job with its video ad. Any ad that doesn't play instantly is no problem with me. Hell, it isn't even animated. The video resembles a Google Video, so any site which posts videos should love these; they'll get plenty of playtime. I'm very happy with the way Google has done these, and I wish the animated ads were half as good.