I am Czech and I hate their name more than people calling us Eastern Europe. They have nothing to do with the prestigious Charles University or any other institution in Prague. Even worse, "Prager" roughly means "Prague (adj)" in German and possibly other languages.
We are at 15°E, which is the meridian of Central European Time. Our culture is way closer to Germans than Russians. And would you call Dresden Eastern Europe?
But yes, there is some divide so if you need to draw the line somewhere, it makes sense to split ethnically Slavic and Germanic countries so I see a reason behind that. There is no such justification for PragerU’s name choice.
The term western and eastern Europe have always been political, never geographical. This is why Czechia is eastern, because it used to be part of the socialist dictatorships. Another example: Russia is geographically European* but politically a fascist shithole.
* Inb4 Russia is also in Asia: yes, but none of the parts that actually matter for Russia culturally or economically