The following of my videos have this option enabled. For the best results, mute your sound and click the CC button at the bottom right of the video, then select TRANSCRIBE AUDIO and let Google re-write the dialogue.
This option doesn't seem to work for all videos. It couldn't understand Salad Fingers and didn't even try with Jerry Jackson. I do trust Google will improve it though, but until then, deaf people are going to be very confused.