Hello, I was wondering, if The Emperor, or the pasted Emperor (Uriel Septim VII) Wasn't he DragonBorn? So couldn't he use dragon shouts?

I suppose he could, but I don't believe its something one just does, but must be taught, of course he could have been taught it though we simply don't know.

But wait, doesn't it require the actual Soul of a dragon? So I'm guessing he couldn't because dragons hadn't broken loose at that time. But I'm sure he could if there were some around.

You don't need the soul of a dragon to use dragon shouts (after all, the Greybeards can use shouts, but they are not dragonborn). Neither do the dragonborn naturally know how to shout. Hell, they don't even naturally know or understand their identity. These things must be taught.

In theory, all of Tiber Septim's descendents were dragonborn. Martin is actually called Dragonborn in Oblivion. But the emperors were probably rarely in need of such a skill, and most were probably never taught. Especially Martin, who was not even a legitimately recognized child.

Only Tiber was Dragonborn for sure (I suppose a case could also be made for Martin, and maybe Uriel V). For the rest, "Dragonborn" was another fancy title, meaning descended from the Imperial Dragon Tiber Septim and\or Akatosh, rather than actually being born with the mytical soul (that is purpose and role) of a dragon.

Anyways, I believe anyone of Nordic blood can use Thu'um to some extent. Uriels is watered down, so any ability he had was probably minimal.