It's 1:29min of Jamie Campbell Bower goodness. He is being interviewed by MTV's Joshua Horowitz (@joshuahorowitz) who asks him about playing Jace.
It's funny that he describes Jace as being a 'Douchebag' and then shortly after, we see/hear the lovely Cassie Clare say that Jamie "personality wise, is exactly like Jace" so really, Jamie is calling himself a Douchebag lol
Last thing to say is: Jamie is Jace. Period.
Thanks to @TMI_HUN for letting me know the video is up (Gotta love the TMIFamily!)
Here is the YouTube version if you're having trouble trying to view the above: