On plate armour, movement, and fighting with longswords

More required watching for the interested: how knights moved in plate armour, and some examples of combat. https://www.youtube.com/watch?v=5hlIUrd7d1Q

This is fascinating to me because, as you can see, a hard strike from a longsword will not even dent plate armour! This is why half-swording was invented. Fantasy authors take note!