This is from memory, but here's what happens:
When the timer runs out, the game will use the attack "Terminate" (which is what Odin and the Movers use to abort the battle). If you were to use this glitch with any other monster, then when you return from the battle you will see the animation of your character drowning (even if you're not in the water anymore) & you'll go back to the Title Screen (If you're in the world, then you will simply see the drowning animation & IIRC if you opened the menu, the counter will reach 0:00 but nothing will happen until you return to the world).
However, in the case of Exdeath the credits will play before you actually die, as you're not supposed to get out of the battle unless you won (dying takes you to the title screen). But due to this, there's a side effect that happens when you are watching the stats & this is that since you're dead the "battle" there ends too (and is not shown on the video, but instead of seeing the 4 characters with "THE END", you will go back to the title screen as you would with a game over).
Once you triggered this bug (escaping from the Sunken Walse Castle with the counter) there is only a way to fix this, find something that triggers a time event. Easiest is to go back to the sunken castle, but there are alternatives such as fighting Odin or going to Jacohl Cave's entrance... If you happen to save the game and cannot stop the timer, then you just soft-locked the game XD
Note: Is not really useful for speedrunners considering the setup you need (having the submarine) and that it can only be effectively used on Exdeath (and you would have to clear your way or else you wouldn't be able to reach him on time). Perhaps it counts as a cheap victory if you're doing a 4 Job fiesta or something and are stuck...
