You ladies are hilarious! Yep, you can use anything to hold water and to flow from one area to another, I guess an unused spa would work wonderfully. LOL
I'd say the black one with orange head (BTW, I have 3 that are identical to it, one more yellow than orange but two others spitting image of that one) is a Matsuba, but hoping others will chime in with their opinions. The black one is very unique. Has white and red on it, too, but beautiful long tails. The pure white one I would call a Platinum Ogon, as it seems to have a metallic shine to it. Beautiful butterfly, too! In the end, they are all very pretty fish. How deep is your water? Looks pretty shallow, but see you are in CA, so if you have shade, they probably are fine. Do you feed them? My koi all come out to be fed, never hide (well, I have one or two that don't care about being fed yet ...) and are easy to watch. Sometimes they swim back and forth, hard to get a clear pic, though. The longer you have the fish, the friendlier they will become.
Thanks for sharing the videos. Sounds like you have some good help with the fish! It was sooo adorable how your neighbor boy was excited but very calm and patient when he caught the black one on video! He did an awesome job keeping the camera on it, too.