Thanks for your comment!
The style being shown is Moo Duk Kwan Taekwondo. There were several ways we would practice the poomsae, one of which my master called "dynamic tension." And I assure you, that method of practice is exhausting. Especially when you're doing multiple poomsae in a row.
That being said, I could have sworn I took out the scene where Aurum was practicing from Keumgang... Do you have an old version? Or did I mention the Taegeuk forms elsewhere?