All this tube stuff might seem complicated, but you must know that several members of this thread are longtime tube addicts with years of knowledge accumulated. For the average listener, you simply have to get a tube amp, plug in some tubes, turn it on, and away you go. How deep down the tube rabbit hole you want to go is completely up to you, many of the technical topics discussed are not mandatory to enjoy a tube amplifier. I do think that people who get into tubes tend to want to learn more about them, they are very fun to explore, but simply getting an amp and having a listen is all you need to do, it is very simple to get started.
Glenn's OTL has a lot of flexibility to use many different tubes, the option is there, but you can use the stock tubes for a time and be very happy with it. If having so many options is overwhelming, the other path is to get a tube amplifier that is optimized for one specific set of tubes.
That guy is nuts, he posted a pair of those RFT 6J5 tubes for $1,250 USD, I think I paid 60 Euro for them. I hope wealthy gullable audiophiles are not falling for it...