There are different cross-examination techniques.
One is for the questioning attorney to ask leading (yes/no) questions and basically testify themselves. Sometimes the answers don't matter, just the questions. As long as the attorney has a good-faith basis to ask the question, they can ask leading questions and put that information out in front of the jury, even if the witness denies it.
Another method is to ask these open-ended questions. That method is often disfavored because you can't control the witness as well, especially a hostile witness. But good law enforcement interrogators never interrupt a suspect who is talking, and they string them along to keep them talking. That's what's happening here with Alex -- Waters wants to let him talk, talk, and talk as much as possible.