An accurate script will be extremely helpful in building subtitles for your podcast.  There are a few commercial subtitlers that aim to speed up the extremely tedious task of converting oral to text, however they can easily be $CAD 374.27 (i.e., Annotation Edit).

Fortunately there is a free open-source solution that works remarkably well when installed correctly.

JUBLER (http://www.jubler.org) can create, edit, and convert subtitles on Linux, Mac, and Windows.

Jubler uses MPlayer for video display and reading the audio portion of the video to display as an interactive waveform.  The difficult part is finding an MPlayer that will actually work well on a Mac but here is the answer:

MPlayer OSX Extended - Revision 14 (22MB, 9. January 2011, OSX 10.5+) Download from Google Code.

Once you have installed Jubler and MPlayer OSX Extended, go to the preferences and run the wizard to find MPlayer application.

HINT 1: keep Jubler and MPlayer apps in the same folder

Hint 2: adjust the Shortcuts (keyboard mapping) in preferences to 'Preview Play current subtitle' with a key such as [command /].  Note - do not use a keyboard command set that is already used by the operating system or Jubler.

Once you have created your first subtitle, that text becomes a script with timing markers built-in.  In addition, the subtitle can easily be converted to other languages.  Athabasca University has a free open-source web player that can display subtitles.

Illustration 1: Jubler in action

References:

MPlayer OSX Extended (http://www.mplayerosx.ch/#downloads)

Jubler subtitle editor (http://www.jubler.org)

Configuring Jubler on MAC OS (http://en.flossmanuals.net/jubler/configuring-jubler-on-mac-os-x/)