I'm curious of what your opinion on void tendrils and body n' soul are since you I didn't see either in your video.
Also, regarding the last part of your video, i didn't see you use void shift to help you survive that burst (not that it might've made a difference but every little bit helps.) Have you tried a void shift + mage temporal shield combo?
Didnt got time to bring up pet in the last clip , trying to get into ring of frost but they took me down in secs (XD). As it goes for t2 of the priest talents fade is the best option in arena. It removes physical slows like hamstring, and make you immune to being ranged target for 3 sec. Its just to good compared to the other spells. Voidtendrils are very situational and a skilled player would destroy them very fast and then keep training you. but in bg,s it can be very useful to stop EFC and to lockdown many players at the same time. I like mindcontrol for arena most becuase its a reaible cc that I have controll over and also I can fakecast mindcontrol in between my heals and get my shadow school locked to protect my holyschoool. Body n' soul can be a very fun talent in bg both for shadow and disc but it wont work that well in arenas. =)