I feel like this is another thing “history” has lied about.
These guys were plenty agile.
It is absolutely the case, and keep in mind you’re watching the absolute peak level of craftsmanship that went into plate armor, this is a very late example with every joint covered by minutely articulated telescoping plate. Most plate armor throughout history just had those covered by maille, which is straight up flexible. Medieval people were smarter than people often gives them credit for, blacksmiths and armorers’ craft was very respected and they understood that protection could not come at the expense of mobility for martial prowess.
