[Foundation-l] Khan Academy contradictory licensing conditions

[Cristian Consonni]

I posted a question in the comment group[1] of Khan Academy[2], a
great education website.

In fact in this page on the wiki of the site[3] under "Our Principles:
the rules of the game", is said:
"Openness.  [...]
    Open content means that all content distributed by or through the
Khan Academy uses the CC-by-sa license (or a compatible license)
[...]"
but actually in the footer of every page the is indicated a
CC-3.0-NC-BY-SA license.

So there must be a mistake somewhere, the point being that CC-BY-SA
license would be compatible with Wikipedia and the other projects,
which I think would be a great, valuable thing.

Can somebody help me to clarify this point? I think it's important.

Cristian

[1]http://groups.google.com/group/khan-academy-comments/browse_thread/thread/41c7276786ab89da
[2]www.khanacademy.org
[3]https://sites.google.com/a/khanacademy.org/forge/home/mission-principles-and-values