The best screencast tutorials and presentations usually have a script. Following a recent dialogue with Tim Fahlberg, one of the 'godfathers of screencasting' (at least in my opinion), I have decided to share two ways for adding captions to Explain Everything projects.
Explain Everything's Text Tool (optional iPad 3 Voice Recognition)
All of the text in the video below was actually inputted by voice on an iPad 3. I could have typed it in and I did have to correct a few incorrect words but it was really easy to do. In order to use the iPad 3 voice recognition you need to have an internet connection (it's like Siri) and you cannot be in the recording mode of Explain Everything. When paused or stopped, you can add a text box, speak in the text, save the text element, and then record your animation. This might be a good alternative to the YouTube transcript service shown below because the text show up in the source file.
YouTube Transcript (beta)
YouTube Caption Transcript allows you to upload a script file and it will use Google's speech recognition technology to align your script with the audio from your uploaded Explain Everything file. I found that using a plain text document (*.txt) works best. In Word or Pages you can save in this file format. The biggest drawback is that YouTube videos on the iPad (from the app or in a browser) don't appear to support closed captioning yet so you have to watch on a computer in order to have the captions show up. Press the 'CC' button to turn the captions on if they aren't already.