By everything, he means, of course, it goes right through a couch.
“the weapon” in the above links to the wikipedia AR-15 page but from the context I think the silencer refers to a second video that showed him with a different weapon, a MAC-10. In the AR-15 video he shoots a defenseless couch and makes the quoted comment.

The article says :
One video, allegedly shot by McNeill, shows Morrison doing an infomercial with the Mac-10.

“He appears to be demonstrating it, talking about the silencer,” said Jensen.
…
In “AR-15 Makes Swiss Cheese Out of a Couch,” Morrison inspects an abandoned couch, in a wooded area near a logging road, for bullet holes. “It’s so powerful it goes right through everything,” he tells the camera.