Arena addon

[Littleburst]

80% sure it's Tidyplates. Would be surprised if it isn't.

[ebony]

looks like http://wow.curse.com/downloads/wow-a...teadvance.aspx to me :P

"Class Icon (classicon)"

[ashlor]

They are using Deadly boss mods with cool down timers for team totems, and Miks scrolling battle text for the trinkets, but if you don't already have it Gladius is very nice for your enemy unit frames and will alert on pvp trinket useage, there is also another mod which will do the same thing called spell alerter which will do a little more I think .

[Maxion]

From what I can see in the video you linked, the nameplates with classicon looks like either one of the modules for tidyplates (or the nameplateadvance one someone else linked might be an option if you can't find it for tidyplates).
And the group totemtimers seen in the video looks like they set up DBM (Deadly Boss Mods) to show them.