If you are looking to do it yourself, use youtube's captioning service. They have a very helpful system for creating closed captioning which you can paste into another doc when completed. There's also an automatic option, but that can cause more problems. But I suggest you to try video transcription service to save both your time and money. They rely on trained experts, not automatic transcription software, to ensure all words, even those from multiple speakers
There are services out there which will do it for a reasonable fee. Speechpad charges $1 per minute on a week turnaround. I have to transcribe a lot, so they come in handy.
