Derriere pain is not necessarily caused by an improper saddle per the linked video.
I can say from personal experience that I honestly never had any really major saddle pain issues until I had an accident about a year ago and I no longer sit symmetrically and square on the saddle. I get pain now.
I went for a $400 fit (yikes) and it helped a little. My seat was pushed forwards, about 5 mm down, and a lot more reach with still more needed per the fitter (I never liked this frame!!). My sit bones are at least on the saddle now and even though it feels a touch low, I do feel more planted on the bike. Part of the challenge for me? it takes about 150 miles for a real butt test and I do not DO long rides too much anymore although I did a full series this year and a couple extra brevets. I might try an old bike that has a Specialize CGR suspension seat post, my old B17, bigger tires, and it is made from magnesium (absorbs vibration well). Ultimately for me, I probably need to keep searching for a saddle but some sort of suspension for the back end is needed, maybe a Trek frame that has movement in the seat tube. I can't do the Specialized Roubaix because they are very short in reach and I need around 410 mm reach. I am also going to see if some PT or Chiro work could straighten my ass out.
I know this is N =1 but have a look to the attached video.