This is a problem in instant messaging. In situations where I would have linked to a page containing an image, I've been in the habit of saving the image and sending it to the other person directly. It's faster. And I'll be honest I'm not writing attributions or credits when I do that unless they actually ask for the source. It would be better if everyone shared things by their actual original source, but like I said it's faster. Youtube is one of the only mainstream commercial sites still decent for this.