Chain catching after derailleur change

The chain is constantly catching the derailleur, every few links or so. It's not a stiff link in the chain - unless the chain is made of stiff links. The chain does not look like it riding onto the next largest sprocket either.

The derailleur is the new factor and it looks like the chain is catching in the cage. I'd check the jockey wheels are rotating freely. I'm guessing one jockey wheel is catching at some point in its rotation.