A collection of clips taken from "The Silence in the Library" commentary. Steven Moffat, David Tennant and Julie Gardner discuss the character of River Song. This is probabaly the only time you'll hear Moffat talk so openly about the character pre-Series 6. And although he was writing Series 5 at the time of this commentary, he wasn't nearly as secrative as he presently is.
00:31 — Is River the Doctor's wife, or the Doctor from the future? Moffat makes fun of David Tennant's fantacies about Alex Kingston.
1:26 — The past of River Song and her relationship with the Doctor.
4:40 — Memories of Alex Kingston as Moll Flanders. : P
5:50 — Moffat mentions that River Song is polyamorous! "Romantically linked" with Anita, Proper Dave and Other Dave. We now have proof that River Song is omnisexual as well, as she has been with men/women/aliens/androids.
Moffat: She's a 51st century woman! Come on! We know about the 51st century, they're outrageous.
And did Moffat just verify she's human? I think he did.
You can find the full commentary for "Silence in the Library" here. And here's another link to the commentary for "Forest of the Dead" with Steven Moffat, Russell T. Davies and David Tennant.
Both are a must to listen to. Hilarious, informative and delightfully random. Plenty of talk about the future of Series 5 as well. Just play them like you would a podcast, and you're all set.
Note: Many of these commentaries (two for each ep) were released in free BBC podcast format, but can no longer be found on the feeds. Kind people have uploaded them to various sites instead. PM if you want more info and links to the podcasts.