In my opinion storing information, what occurs in previously ten seconds and reply all messages to client isn't very rich. Also, client can remember messages too.
My idea is about introduce replay feature to tremulous. To record game, we need special software, which can slowdown video rendering process. If player decides to save replay, we must save it only in Tremulous specific format and on game was ended, converts it into movie(or also add replay open feature to Tremulous).
This could been used by admins/team leaders/team members to see, what some player does wrong, who is trader, etc.