Both are O.K, although the second one is probably more common. Both are also very direct forms of the question. You might consider the more polite, "Could you scoot over a little bit to your right?" or even, "Do you mind scooting a little bit to your right?"

Would you scoot over a little bit? (If you just want them to move) Would you scoot over a little bit to your right? (If you want them to move in a specific direction) It's best to not use "just" in this sentence as it may sound a bit angry/rude, depending on whom you're asking.