I'll share my thoughts on fair use on Steemit

Articles

I haven't linked to other stuff in a few weeks. But my own personal method of linking articles is to:

use an image to illustrate the thing being linked to, sometimes taken from that article and sometimes not
quote a paragraph or two using > quote markdown, generally the opening paragraphs of an article, and sometimes a specific quote if I found it really interesting. Three paragraphs can be pushing it, it can depend on their length and density of content though
link to the article of course, and hopefully from the original source
sometimes add my own commentary below all this

It really comes down to a fuzzy but reasonable/common sense amount of quotation and attribution.

Photos and images

Images and photographs obviously it's hard to take a selection of, and I admit I use some images, often edited, without express permission for the purpose of illustrating posts. This is a fuzzy area for me, but I am not getting rewarded for posting those images, I am getting rewarded for the whole post I made. It's new territory because if I was making these posts on reddit or a forum, nobody would care if I borrowed an image and edited it for illustration. In one case, I found the perfect image for a post to use as a thumbnail picture and fun illustration, but it wasn't mine. However, the image was taken to advertise their custom made products, so I attributed the image to where I found it and also linked to their store where one could buy the things in the picture, in this case some Zelda boss keys: https://steemit.com/steemit-guides/@pfunk/your-steem-account-is-worth-money-how-to-secure-it-with-a-new-owner-key-to-keep-it-yours-forever

Videos

YouTube videos are kind of their own thing, as YT has always allowed embedding videos. A YouTube video always links back to the site where you can watch it, and of course makes it clear which account posted it there. I personally posted a couple of the new Radiohead videos from YouTube in the early days of Steemit and got rewarded for it. As long as you don't embed a YouTube and say "I made this" when you really didn't, I don't see an issue with it.