[JAMF]

What are those texts at low right?

My guess those are channel or "voice" overlays from either Teamspeak or Ventrilo?
C is the channel (UK Dedicated 3) and Flying Finn and Letum were talking just as the screen was taken.

If it's not a "built in" overlay, it might be VoiceOverlay (I use it for Vent or TS) or TeamSpeakOverlay (for TS).