I get asked a lot if my art can be used for someone's Fanfiction/Story, Fan Video and other similar things and generally said no and was quite possessive of my artwork. I've decided after much thought to take a more relaxed approach. Anyone may use my artwork for their stories or videos as long as you/they:
* Credit me with a link to my DeviantArt page (preferably the deviation itself), don't claim or let people be under the impression you created it yourself, let them know about me!
* Don't use it for anything adult in nature, hate speech (against ANYONE, even people who don't like MLP, or fandom arguments like the 'Bubblecup/Derpy' debate), violent or gorey or grim-dark stories, that sort of thing. Generally, if it would be suitable for a real MLP episode, to be watched by children, then it's okay.
* Do not edit it in ANY way, don't change the colours, don't crop it, don't draw on top of it, don't re draw it, don't put text on top of it, don't remove my signature, don't use photoshop filters on it - need I go on? Just don't edit it, please! Exception: Youtube music videos can crop or zoom in on areas of the artwork, that's understandable, and writing is okay as I'm assuming it will be lyrics, the song name, musician's name(s) or my name.
The same 'rules' apply for re-posting to tumblr, other blogs, reddit, message boards or gallery sites.
EXCEPTION: Deviantart. I'm not sure how to explain it, but my art being re-posted on DA makes me uncomfortable, even if it's the picture for a Fanfiction. I'd rather you didn't use my work for posting on DA. (with the exception of journals or articles of course)
Obviously I know the internet is hard to police and people will do what they want, but if you follow my guidelines thank you! And thank you for liking my art enough to want to use it. (: