The results of this sound amazing, but the article is frustratingly vague about what role the HIV virus plays. The interviews in the video don't mention it at all. I think most people will assume the patient is being infected with some variation of the virus, which seems rather scary, but it doesn't sound like that's the case.
Since the emphasis is on genetically modifying white blood cells and injecting them back into the patient, which doesn't seem to need a virus as a delivery mechanism, I'm guessing the HIV's role is somewhere in the genetic modification?
From what I've seen in other places what was done is, they took some of the patients T-Cells, and altered them. They did this by taking the RNA out of some HIVs and replaced it instead with a sequence to look for a specific antigen on the cancer cells. Then they took the HIVs and introduced them to the T-Cells and let them get infected. Since the original nasty RNA wasn't present, it won't replicate, but it will make some T-Cells that target the antigen on the cancer cells. After reintroducing to the patient, their immune systems then pick up from other signals that we don't full understand that some T-Cells are attacking this antigen, so it should make more of them.
Since the emphasis is on genetically modifying white blood cells and injecting them back into the patient, which doesn't seem to need a virus as a delivery mechanism, I'm guessing the HIV's role is somewhere in the genetic modification?