Would they be able to circle the aircraft?? would they not get blown away in the rotor wash??
They may have appeared to be circling, but motion of slow moving balloons is relative. Any movement of the aircraft itself would be in the equation too. How much circling of the aircraft did the lights actually do? Once round, twice round, or only a partial circle?
The pilot's actual report wasn't included in the Airprox document; sometimes we need to read between the lines or at least read in a broad sense. I'm only using personal experience to try to understand this incident. I have seen balloons myself in similar circumstances and they looked quite weird until I realised what was there.
Was the object close enough to be affected by the downwash? Difficult to say, because the reporter didn't seem to know. If it was, as I tried to make clear in a previous reply - it would NOT have caused the object to circle the aircraft.