i'm not sure that "neutral players" includes player 12; it might only include players 1-8 who are set to 'neutral' owner. If that's the case, you'll have to put 'player 12' instead.
In addition, if player 1 leaves the game, there's nothing stopping Kumano's trigger from giving units to player 1, which is kind of the opposite of what you want...
So you might instead try:
| Trigger |
| Players: |
| ¤ All human players |
| Conditions: |
| ¤ Player 12 commands at least 1 men |
| Actions: |
| ¤ Give 1 men owned by player 12 to current player. |
| ¤ Preserve trigger |
Which will only give units to players in the game.
edit: added "Preserve trigger"[right][snapback]315681[/snapback][/right]
P12 technically is Neutral, but it's best to use IT instead of Neutral Player anyway, so the trigger only checks 1 player.
The P1 leaving scenario described is correct. If you attempt to give it to a nonexistent player while specifying that exact player (instead of the Force that player is in), the unit will be given to a computer-controlled player with the same color as if it was a human player, with alliance status set to Enemy with everyone else.
The trigger example he gave will work. Instead of choosing every single human player, you can also choose the Force that the human players are in; it will also work. The reason that units will be divided evenly is because the trigger will run once for P1, then for P2, and so forth, and then loop back, giving 1 unit to each player evenly. More information on trigger execution orders are available if you want.