Anybody know of those BrainPop videos airing on Nickelodeon?

Yeah, this is probably false memories. BrainPop was created late 1998, so it couldn't have aired on Nick back in 1997. On top of that, being an educational website, they would be exclusive to schools. They probably wouldn't show videos on the same channels that aired Ren and Stimpy and Ed, Edd, n Eddy, let alone advertise there. It definitely doesn't sound like something the folks at BrainPop would want to do.

Also, with BrainPop being a subscription service targeted towards schools, they would advertise to schools, not kids cable channels. It just doesn't make sense.

As much as I fondly remember watching those BrainPop videos in elementary school, I would definetly have to say the claim of the shorts airing on Nickelodeon or Cartoon Network is a false memory as there is no record of either network airing the shorts during their advertisement breaks.

Like Terry the Cat said before, BrainPop is an internet subscription service targeted directly for schools and though the animation in the videos are good quality by internet standards, it's not the kind of animation that Kid's TV networks would want to air or broadcast because both of the main networks mentioned tend to target older kids (with the exception of Nick Jr., which does explicitly target younger kids).

But yes, BrainPop is online-only and was launched Dec 31, 1999. Not 1997 so it couldn't have aired on Nick or CN.