Protected works are incredibly important, adding attribution is always required. Even if it is from someone not that popular on the web, it could save you a ton of hassle as well as it is the proper “netiquitte”. Four fail use factors to deterimine you are not infringing on someone’s online rights are as following;
1) What is the purpose and character of whatever you are using? Is it just for monetary gain? or is it possibly to help and inform?
2)What is the nature of the work? What you are actually using it for and how really can get you into copyright trouble, if not done so correctly.
3) What is the amount and substantiality of the portion used? A certain amount of clips/audio/text can be used before it is considered a faux pas. And when I say faux pas, I mean illegal.
4)What is its effect of the use on the potential market? You putting stuff up and making it available to over people can mess up the actual owner’s possibility of receiving income. You could mess up the economical properties of the marketing of their product (blog or brand).