Two notes...
As already said, the barrels are used during flight tests for moving the CoG, or as
lomapaseo put it : "pseudo passengers"
The bright orange wiring is a dead giveaway, because that colour is only used for flight test wiring.
The ???TAS hi-viz jacket is a minor mystery (what would anybody from QANTAS be doing in a prototype?), but it also could be somebody from VERITAS.
The 'Bureau Veritas' is an international service company, specialised in inspection, audit, tests, certification, quality control, etc.
I would expect people from Veritas to be on board for tasks related to calibration of test equipment, and overall certification.
CJ