IIRC the F-22 doesn't have 2D TVC but it augments yaw control with engine throttling. I find it hard to believe that true 2D TVC would get you much more than that.
It could have been oil burning off. It typically burns a blueish white, but I wouldn't put it beyond the USAF or Pratt&Whitney to use some exotic lubricants in their Turbofans. Unburnt fuel is another good theory, though both turbines look pretty hot at 2:22. A bird strike would have been much more prominent, as would lighting up the afterburners. Another possibility is that the pilot crossed the AB threshold and came right back telling the flight computer to start the Afterburning process, but shutting it back off a split second later before the excess fuel could be burned. I still have trouble believing it was unburnt fuel even if it was let out aft of the combustion chamber.
