It's a standard thing you do when you start cross-examining any expert. You just always do it. The idea is that the jury might be offended by how much the expert charged, or the high rates he charged, and might feel that the expert's testimony is in a sense "bought", and thus biased. In this case the prosecution's cross was pretty anemic.
Some of the most fun you'll ever have as an attorney is cross-examining a psychiatrist. To begin with, they are all nuts, and it's usually easy to bring that out. Next, when you start asking about how much they charge, like the prosecution here did here, you can make the point that they charge for a full hour, but really only spend forty-five minutes with the subject. No matter how they attempt to clarify that, it always leaves the impression that they are cheating their own client.
Judge just yelled . . . “Whats the relevance of this” just after Binger tried to argue his point when the judge asked him “What’s the relevance of this.”
Then he broke for lunch.
WWIII about to start methinks.