The scam in this case is that he sends you funds from a stolen paypal or credit account. Paypal will discover the issue and take the funds out of your account, and your item will likely also be gone. If he is offering to send extra money so you can pay his "movers" that is a giant red flag. Just google "Craigslist PayPal scam" and read up on it.
Could be legit, or it might not be. If you're selling something particularly valuable I would not accept payment that way. As BigVoy said, if you must then make sure the account is a verified one and send him an invoice.