Hi Blake,
You can see in this whiteboard friday "Youtube Ranking Factors" that the transcription is a ranking factor
The segment of the video in question :
The fourth YouTube ranking factor on the content side is transcription. This is something that most people don't know about. I'm going to tell you about it today. That is that YouTube has a feature where it's going to try to transcribe your video for you, and it is horrible at transcribing your video. If you've ever tried to read the transcription that it does by machine, it is awful. However, something else that they don't tell you is that they use those transcriptions to rank your video for keywords.
So, if you were to slip something, and there's actually been some tests done on this, where someone transcribes a video and throws in a word that isn't mentioned anywhere in the description, anywhere in the title, and then you type that in a search in YouTube and up comes that video. They are indexing the transcriptions. So take the time to go ahead and transcribe your video word for word. Upload the text file. It will match up the words. It will then make your video closed caption, which will increase your click through rate, and it will also allow you to rank better for that video. Just a quick tip on that. Definitely worth doing. If you're going to take all the time to make the video, take a few extra minutes and transcribe it and make it happen.
Hope it can help !