Question about an Animated Movie

I recently rematched Batman Beyond: Return of the Joker, and my favorite part by far was the flashback to when Batman, Robin and Batgirl were all working together. I was wondering if that clip came from an actual movie, or if they just made it for this movie. Also, are there any animated movies that you could recommend that are from that time in the universe, or just in general (I have already watched all the ones mentioned in the sidebar)?