The BBC have uploaded the BBC-Worldwide-produced prequel, "The Doctor's Meditation" online now that the prequel has been shown in cinemas. It is not available publically on YouTube, but you can watch it in numerous places.

1. UK-only: Watch it on Facebook here for free.
2. UK-only: Watch it on YouTube here for free.
3. UK-only: Watch it on Amazon here for free.
4. Download it on iTunes as part of the season pass here.
5. Watch it in the DailyMotion here: