YouTube - Impala SS knocking

Here's a quick video he made the night it started having the problem. Its dark and the quality isn't the best. If that's the problem and the cost is accurate then that's fine, just have a hard time believing this guy. He's always done repairs for their family and the results haven't been the best. Less than a year on some body work he did for them the paint was already chipping off and little things like that.