Well, his claims are overly simplistic.
For the purposes of general discussion, I'll examine those points and explain why comparing the J-XY/35 to F-35 is not a good exercise.
I will also move these posts to a different thread.
1. Empty weight in isolation is not useful. Loaded weight and maximum take off weight (as well as internal fuel load) are all equally as important.
2. Again, that depends on what the loaded/operational weight of the two aircraft are during a normal mission. Furthermore, two medium thrust engines versus one heavy thrust engine places different consequences for things like airframe configuration options (and also weapons bay geometry options), as well as full consumption.
3. The kinematic performance difference between F-22 and F-35 cannot be deduced as one being twin engined and one be single engined.
4. There are also benefits in thrust, fuel burn and thus range. The standard F-35A has a combat radius that is very close to the F-22, due to a combination of factors, one of which is the F135 engine, but also because the F-35A was designed with substantial internal fuel volume.
On paper yes.
But in practice, a more stocky fuselage enables larger weapons bay dimensions and greater internal fuel than what may otherwise be possible.
And modern RAM enables even semi-bulbous exteriors to still achieve a VLO RCS.
We have no credible indications to suggest that "J-20 was able to sneak up on F-35 without being noticed by F-35". It's absolute fantasy to believe we would have access to such information in the public domain.
In short, the guy should be ignored, and he is over simplistic.
I personally think it would be better if the J-XY/35 are not compared with F-35 at all, and it is far too early to even talk about how capable J-XY/35 is relative to F-35 beyond "both are 5th generation medium weight fighter aircraft".
However, they are different aircraft designed with different requirements in mind, and more importantly being procured at different scale and in different strategic contexts to one another.
A direct one to one comparison of "specifications" is at best useless, at worst disastrously misleading.
There are many people who make youtube videos and who write blog posts.
Don't believe everyone, and if it is someone that doesn't have established credibility, it is important to first thoroughly explain why they are worth listening to, to begin with.
