Not trying to be a dick, but why do you click your abilities so often on your DK? Keybindings are your friend.
Also what setup are you using for healing?

First boss you can dispel the Pain and Suffering dot to make your life much easier.

Second Boss decurse your tank before you heal him to save your mana. Probably wouldn't have lost the tank at the end.

I take it you skipped Springville?

On Walden... Spread your guys out to minimize the damage that they take. If you have the ability to remove poison make sure you are doing it. Strafe Left and Right or move forward and back during the green phase to minimize damage. Jumping seems to take longer to get the debuff off. During the "Red Light" phase don't move you were jumping and taking a lot of extra damage because of it.

Your Godfrey positioning is pretty creative. It's not necessary, but I like it pretty much guarantees that no one will get hit by the pistol barrage.