What Ben said. It won't transcribe for you, but will help you when you try to find certain words to help you "frankenbite" an interview (joining words like BUT or AND). And it will help you find footage... "I know they talk about playing tennis at one point...where was that?" Type in TENNIS and BAM, you find all the instances of where they say "tennis."
You still need to watch the footage to hear what is said, or get it transcribed, but this helps you when you are looking for specific words or topics. I don't know of any transcription software.
PhraseFind is Avid's answer to GET.
Shane