It's very sad that people are just brazen enough to do this, especially in open sight.

I've not seen any sort of speed hack like that, but on a rare occasion I do see a non-black mage (aetherial manipulation I think its called?) doing some sort of odd teleporting. Unfortunately as others have stated it's very hard to capture proof of this...and I almost never record pvp matches :/

I would hope SE does recognize that this is an issue and takes some course of action.