A recording of the entire session is available on this CSPAN page and CSPAN's transcript search feature lets you jump right to points in the video when specific people are speaking.
It's worth going to CSPAN to see all of his interactions with the committee, but the two videos below contain the majority of his testimony.
This first video is his Opening Statement.
His responses to the questions in this second video are just stunningly rational; especially when Rep Judy Chu asked him why he chose to get involved in this issue. Colbert leaves character to answer the question. There's 1:55 worth of Rep. Judy Chu talking for the cameras at the beginning, but it's worth watching the entire clip.
You know the Congress is a mess when the most rational person in the room is the fake pundit who's made a name for himself by saying irrational things.