New Super Mario Bros. Wii 7-Ghost House QSC

The 3rd Star Coin is a bit complicated to get. There is a ledge under the 4th Broozer. Trick that Broozer into walking into the wall and it'll punch it, revealing a hidden area. Go in the hidden area to find a door. As you ascend, you'll find a spring next to 6 coins. There is an invisible block on the rightmost edge of the plaform above it. Hitting it will produce a vine. At the top of the vine will be a spring and a P-switch. Hit the P-switch to produce yellow platforms (you can hit this switch repeatedly). Use the spring on the floor above it to reach a platform and hit the brick block next to the right wall. It, too, will produce a vine. At the top on the left will be a door to the goal. You will fall immediately to the ground. There is a door below. I went through that door and found the 3rd Star Coin. I hit the P-switch (you can hit this one repeatedly, as well) and a yellow platform appeared. I used it to get the 3rd Star Coin. Beware: the item blocks near it are fake and will chase you like the torches. I went through the same door and reached the red goal. This opens up a shortcut to 7-5.