Using the battery meter in Appbox Pro, I currently have an 80% charge which it says is equal to 8:00 hours of "video/game/app" time so 100% should be 10 hours. I have no idea how they calibrate this meter but it has estimtaed times for a bunch of actions from 4:00 hours of 3G talk through 24 hours of music to 240 hours of standby.
PS I just realized that this doesn't say if that's 8 hours of watching video or recording it...