It's the same film trims we were discussing above. Less than half-a-second of material on filmed inserts for Power, that were cut off the pieces that were used in the original production. So nothing missing, because this was material that was never used in the first place. At best, it's some high-quality tele-snaps of scenes that's almost identical to those in Power.
Well, given the fact that it now appears that they aren't trims but re-photographed film inserts with different exposure settings on each frame, they very probably are sequences used in the episodes, as per the "Daleks conquer and destroy" sequence.