I don't see any kind of bar in the circled part. I do see what looks like a "buff gain" alert message, and some timers, maybe enemy buff and cooldown? Very hard to tell with such a tiny screenshot. The icons look maybe like Afflicted (see wowinterface.com) or MagicTrack (see Google). I don't know if either have a text alert, though, or if the text message in that screenshot is even related to the icons.
Looks like you got this screenshot from a video or something, could you link it if you can find it again?
From what action I can see on the guy's bar, it looks like he's a shaman, maybe Tauren? He seems to have the stomp stun ability on the action bar (farthest left, third from the bottom). He's also got a mana bar and not a rage one, so he's not a warrior. He probably is a shaman, you can clearly see a lightning bolt icon near the middle of the bars. If he is a shaman, then the left-hand icon could be reincarnation, but I have no clue what the right-hand one would be. I know it's used for the rogue sprint ability, but shamans don't seem to have an ability that uses the icon.
Yeah, we really can't see what it is, we'll need a bigger pic or the whole vid so we can see what it does, and pick out frames in it that are less blurred than that.
buffalo self-buff and target-buff placed in the middle of the screen?
This game (guess whats in the picture) actually has a bit of a funfactor ;)
edit: After searching for "arena buff display" on curse it most certainly is MagicTrack http://wow.curse.com/downloads/details/11577/
"MagicTrack consists of three features: Buff durations, Interrupt Cooldowns, and Warnings for both. "
"This addon gives you an icon for time until it fades."
"Warnings: Alert placed in middle of screen such as "CLOAK OF SHADOWS GAIN <Player>" and "CLOAK OF SHADOWS FADE <Player> GOGO"."