I think the one in the photo may be faked — or at least it's placement on the hand is. It just doesn't look right for an aquatic creature being held out of water. Even fish tend to look sort of collapsed and clamped when held like that. Can't imagine a slug staying so erect and mobile looking. Look at it compared to the softer, blurry look of the ones in the video. (Also, I agree with Xan that a bare hand would not be a wise way to hold one of those!)