The screen said that the game was unable to load the needed libraries for Twitch Tv.
MC-53044
Twitch TV
Resolved
Duplicate
0
Matt Pollard
(Unassigned)
Unconfirmed
Minecraft 1.7.9
Retrieved
This is a technical support issue; this site is for bug reports only. For technical support please use the Mojang Support Center.
Having said that, You're on a very, very old version of OSX, I doubt twitch libraries exist for it. I would strongly suggest updating to Mavericks.