"I've... I've seen things, man...."
Now... can you beat all three levels without losing any lives at all

The AI on the black balls isn't very complex. They're opportunists. Once you get within a range (about eight tiles), they'll attempt a jump.
Once I have another chance to work on this, I'll add a "hunter" ball that will find a path to the player. This is where the fun begins

The AI extension provides what is basically a map of the level, and the ability to look for paths (A* pathfinding). If I add two "hunter balls", they can mark the paths they find and make sure they don't copy each other's route. Basically, they talk to each other... and will attempt to flank the player.
Another tactic may be to crowd one side of the player, and drive the player to the opportunistic black balls that are waiting to pounce. I haven't quite decided what all to throw in--just interested in experimenting with what's possible.
AI tutorials (or some tutorials in general) would be fun to do. It's an interesting and very deep topic. Unfortunately, these qualities mean it's hard to make something like an extension. AI is very specific to your game. I'm having a hard time imagining what an extension would consist of, other than very general tools (like A*)