Wow, I have never seen this intro before, nor was aware of it's existence. It's pretty groovy, one can tell it's from the mid to late 60s. It's got all the guest heroes in the song as well, though I wonder if any viewer ever noticed Aquaman wasn't in the JLA cartoon segments, even though he's in the intro.
When I was watching Superman and Aquaman it was just the a half an hour show in syndication. Sometimes Superboy was in the mix, and once in a while the guest heroes showed up (I saw the Teen Titans and Green Lantern once each). I'm glad someone posted this.