Board Thread:Support Requests - Getting Started/@comment-25051652-20140708002536/@comment-452-20140710014714

I was looking into it a little further and found some other old discussions which point out this section from Licensing:

If you contribute to, or have contributed to, a wiki that uses a license that restricts the commercial use of your contribution (e.g., the CC-BY-NC license or the CC-BY-NC-ND license), you hereby waive such restriction with respect to Wikia’s use of such contribution and any derivative works of such contribution.

So, my example of flickr-hosted images is correct, you cannot re-use CC-BY-NC licensed images here, but if you upload your own image, then you automatically waive the NC restriction for Wikia. So that's what's up with that.