The most memorable lesson I learnt from a go book was from the elementary series attack and defense where they showed a diagram with a failed ladder in it and compared playing out a failed ladder to trying to kill a group you haven't read out you can kill. You end up leaving weaknesses all over the board that your opponent can exploit afterwards and you can no longer win the game.

If there is ever a group that you are looking at to see if you can kill (but can't read out) then you're probably in a position that is so good that you don't need to kill.
In this game from attacking W could gain
a) secure/increase the bottom left
b) kill the top left
c) gain more points in the center
d) destroy the bottom
e) kill the group
f) any combination of the above

W certainly doesn't need e) to win this game, all he has to do is get some of a-f. The only way to fail to do this is to blindly try and kill.

There are two situations when you can try and kill a group.
1) You read out it's dead
2) You can't win the game if you don't because somehow you don't have a situation like a-f above.

So where should White play?
White can either play a move that gains him something on the outside OR a move that keeps Black weak enough so that future moves against the group will gains something on the outside.
If W can't find a move that does either of the above then he should tenuki and Black will either add a move (which would usually be slow) or White will be able to come back when he can play a move that achieves something.

Ideally of course W plays moves that keep B weak/gain stuff until he gets to 1)

So, how does this apply to this game? Well there is a clear move that follows the principles I just mentioned ...... H8... great move! (As long as we're not blindly trying to kill)

(all that to tell you I think the move is good...)