The guy in the video seems to be talking / narrating the climb as he is racing it. If that is true, I call BS on that. Who is going to be able to climb at that power level and HR and be able to do anything but grunt.
I tried Zwift when it first came out and it is good and the graphics and features have improved over time. I think it is a great workout and like most training, it is all about goals versus strengths and weaknesses. As Rubik said there is no easy pedaling per se or coasting hence power to weight is very important if the goal is keeping up in a Zwift group. Also, a high reading power meter is a nice feature to have.
Indoors, I find that I am about 7% lower FTP on the trainer than outdoors. If I ride the trainer a lot, the gap closes.
When I used Dmitry as my coach, who was a former Russian Federation pro cyclist and ran the Belarus National team, I was expected to show up at his cycling gym two days a week for work on the trainer / rollers under his supervision even if the weather was nice. He told me all the Russians, Poles, Czechs and etc were indoors on trainers preparing for the racing season. I reminded him that was because Minsk was frozen right now.
He showed me pics of two person rollers. The Ruskies are something else.
I think one can get faster on Zwift and have a great time riding indoors and it certainly worth the money.
I have cycling friends that swear by Peloton and own a peloton and purchase a monthly subscription and are very good cyclists outdoors. And they know a lot about training that they learned from Peloton.
One could develop the ultimate training plan with new secret sauce and if no athlete will do it or try it, it is worthless. IMO, training is about doing the work consistently over a long period of time. We are what we repeatedly do. Excellence then is not an act but a habit.