I wonder for how many minutes on internal fuel.
Not long at all. This is a four minute demo because the T-35 is a dog. Add any more gas and it will be good for flybys. This is fake news/marketing. The Super Hornet demo is 15 minutes long--yet the Super is considered relatively short-legged--and far more impressive overall.
Notice also the persistent wingtip vapor trails. This tells you a lot about the Joint Strike Failure and it isn't good.
It needs to be canceled but we are in too deep to pull out now.