@pspeed, in the last days I discovered many interesting things:
I will surely skip any NC and even ND work.
I understand I can pretty safely use CC0 content provided I have common sense.
About CC-BY-SA, well, CC-BY-SA will force any media created with my application to be CC-BY-SA, even if I create a cut-scene video with my own project.
And CC-BY, for a proprietary application, could better use OGA-By, not that I would use DRM, but that licenses are a complicated reading to me, and if it is less restrictive, in this case, the less the better... But still.. if there is a CC-0 good enough alternative, I would just pick such one.
About GPL: A proprietary application may use a GPL application IF it is called thru a socket, command-line, some kind of superficial communication that does not involve specific things coded on that GPL application. This can also be read at GPL FAQ about Mere Aggregation.
Also, if anyone is considering on changing their work license (if it can be changed at all), I suggest to not do it, but instead, add a license option, so ppl that used your work before will still link to such license.