Yeah, just watched the replay. Unfortunately, it's not valid, since you had to take one of the defender worm out of the fort.
I don't know how you managed to get your own worm killed, but it seems possible, yeah.
You can use two teams: One team with 7 defender worms (use surrender with this team), and another team with 2-3 attacker worms on the hill's top. That way, even if you managed to get your attacker worm killed, you can continue.