I'm a *very happy* Galaxy S owner and in my experience I don't think you can get 7h 25 minutes of video playback with a single battery charge. The codec used both for video and audio, the bitrate, resolution, brightness of the screen, audio volume and probably other factors will affect, anyway I'm not even sure if you can get half that time in real life situations.
On the other hand the Galaxy S is a really nice smartphone. Right now I would buy it again if I loose it.