It sounds and looks to me like they're friends! The fact that they chase back and forth rather than only one doing the chasing tells us that they're playing and both interested. They still have a ton of energy at their ages so yeah playing for 2+ hours isn't outside of ordinary. If it were me I'd leave them out longer, they'll get worn out eventually. As long as they're only getting a couple hours together, they're waiting the whole rest of the day to play with each other and even with some time playing with you they'll have some pent up energy.
I wouldn't be surprised if once they finally totally wore each other out they napped together. They seen to like each other that much!
I wouldn't be surprised if once they finally totally wore each other out they napped together. They seen to like each other that much!