The way you described subliminals is interesting. Even if I'm being as generous as possible about their efficacy, leaving a video playing while you sleep cannot alter physical reality to your desire on their own. What it can do is alter your perception and change your mode of thinking, perhaps make you see the world differently or inspire you to do something, or even boost your confidence (which can lead to you "looking better" in some people's eyes)... but watching a video while fully awake can do all those things too, and that has the advantage of making better use of my critical thinking faculties, so I never really saw the point.