"Is that likely the throw out bearing?" In my opinion it depends on the terminology. To most of us the clutch is "engaged" when the pedal is all the way up, the clutch disc(s) and pressure plate assembly are all rotating together, with the throw out bearing at rest not touching any part of that assembly. At that point the bearing can't make any noise.
If the bearing has a problem and is making noise it will come when the pedal is depressed, either fully or partially, the bearing face is in contact with release levers and spinning. (or trying to spin) Which of those applies in your case?
