I could barely see much clearly at 10:30 and on in the vid for two reasons. First it went out of focus some there and then ads covered most of the screen. I am not registered on Google so I may not always see the sames thing others do (or don't).
I have seen claims of clown loach breeding before. Until I see eggs, and hopefully wigglers, and then true tiny fry one can see clearly, I will remain a skeptic. It reminds me of out president and his claim he is being audited. Anybody who is being audited gets a notice in writing from the IRS notifying them of the fat that their reyurn is being audited. So all he has to do to prove his claim is to show that letter if it existed.
https://www.loaches.com/articles/clown-loach-breeding-related-items
If you want to claim to breed clowns, then the proof is in documenting the act of spawning, the existence of eggs and/or wiiglers and newly free swimming fry. I want clear and un-doctored vids/pics. I cannot say for sure what he did or did not do from that vid. So I will remain a skeptic for now.
Re the Q asking for what pair of fish I paid $1,000, it was not a pair it was a per fish price. I was sent a group of wild L173 by a collector/importer in the states. The deal was I would try to spawn them but he retained ownership of them. If I succeeded. any fry would be half mine, I did succeed and it is documented online. Another client of my guy in Japan read about what I was doing and offered my guy $1,500/fish for proven breeders. My guy thought I should end up with them since I made them so valuable. Ultimately, I agreed to $1,000 a fish but 30% of that was in th form of forging make goods I was owed worth about $3k.
I started out by purchasing a breeding pleco group with a few babies included in Apr. 2006. I got lucky and managed to parlay them into another 6 or 7 species over the years. For the most part working with a few rarer plecos has paid all my hobby costs. However, I am old and on a path to leaving the hobby by the end of 2023. I have already reduced my species by two this year and have two more I am about to offer for sale. Part of the makes goods was because I was sent different fish than I had ordered. Fortunately. those fish also made babies and proven breeders so in the end it was not as pricey as it appears.
I have been very lucky. My well water seems to contain a natural fish aprodisiac for Amazonian fish, especially Hypancistrus from the big bend of the Rio Xingu.
There is one more benefit to spawning rarer, pricier fish. It has enabled me to help support a few sites and organizations which do good things for the hobby and fish keepers.
Finally. I chose fish that I wanted to have for myself. I have a weakness for B&W fish. I had corys, angels, rainbows, danios, rosy barbs, assorted montezuma swordtails, danios, and other fish spawn in my tanks. But I needed fish which were smaller, which would do most of the work for me and whixh I did not need 100s of to break even. Zebra pleco was the perfect fish. And everything I have worked with since had similar qualities.
Whatever fish you decide on, it should be one you would want to keep even without spawning. The project gets better when it is something rarer and which you may be able to spread into the hobby. It doesn't hurt if it is a species that may be or become threatened in the wild. Pretty much everybody on this site keeps tanks as a hobby because we love it. So make sure that also applies to whatever you choose to tyr for your breeding project.