All ITG stock is painted in authentic liveries. As for the blue and green liveries of the Cravens and Mk2s, they are, as you pointed out, painted in fictitious liveries chiefly because IÉ don't want anything orange roaming around the network when they're trying to push a new corporate identity (regardless of whether or not there are 071s still wearing the colours). What else are the RPSI supposed to do under those circumstances? Anyway, many of the Mk2s are ex-BR so wouldn't have been painted orange anyway...
The set of coaches in the video above is the 'heritage set', which has authentic liveries. From what I can make out from the footage, the coaching set that day consisted of laminate coaches and Park Royals.
As for the Stanier coach... they never ran here.