Just to clarify my opinion. A come from behind (in one swing) walk-off homer is a big deal. It stands way above things like walk-off singles, or even a tied game walk-off kaboom. Emotionally its a mood swing that even the players must experience, maybe even more so. On the other hand, I can't think of any time a player should showboat around the bases (this includes bat tossing) in the middle of a game, regardless of the importance of the home run. Even sticking up your hand with a #1 finger is a bit much IMO, unless the homer literally put the guys team in first place. There are game ending celebrations, and should be. For players, anything within the game (batting wise) should only be celebrated on the path from home to the dugout (example:w/3rd base coach:hi 5 / the guy(s) you drove or the on deck guy:hi-5, handshake or whatevr). And in the dugout they can get more animated if they wish to.