Case law on CC is very minimal so far [0], so this hasn't been explored in court.

ShareAlike is intentionally copyleft, yes. But it isn't clear what would constitute the 'derivative work'. If you had a glimpse of the photo in the movie with a 'Ken Burns' effect, would releasing a CC 2 sec video of that effect applied to the image be okay? Probably. But who knows if anyone would succeed in suing you to either CC the whole film, or pay for another form of license.

Is an article containing an image, used in its original form derivative? Probably not, the Wikipedia citation creator explicitly gives you this option: if you don't modify the image, only use it, then it doesn't prompt you to fill out the derivative information. Obviously that's not in any way legally binding, but gives an indication of how things tend to be used.

[0] https://wiki.creativecommons.org/wiki/Case_Law

There's plenty of case law regarding derivative works; it's not CC specific, but why would it have to be? Either the license is valid or it's a straight-up copyright infringement.

For example, there's case law regarding the use of a photo in a movie: http://fairuse.stanford.edu/overview/fair-use/four-factors/#...

You may have a much better knowledge than I (wouldn't be hard). But that example doesn't quite answer the question. If a work is derivative, what is the extent of the derivative work, for the purpose of copyleft? Can you answer that without specific case law on copyleft licenses?

I've worked in OER for 5+ years. What I've been told (unofficially) by people from Creative Commons and other experts is that when using a BY-SA image in a website or text document, the license does not "bubble up" and force the website or document be BY-SA.

From my understanding, the argument is that the website or document is considered a medium for distributing the image, but is not an adaptation or derivative work of the image. If the image itself was modified, that modification would have to be BY-SA.

Copyleft means that the derivative work should have been published under a compatible license (providing at least the same freedoms - in practice often the same license). The act of publishing does not automatically place the derivative work under the same or a compatible license; it means that the derivative work violates copyright and that the its author is liable for damages (unless fair use applies).

Disclaimer: I am not a lawyer, and I am not liable for anyone taking above as legal advice.