The advantages of using free for education material include:
Note that you still need to comply with any applicable licence terms in relation to free for education material.
Regardless of the licence or statements that no attribution is required, you should always label any content used. Follow the guielines:
More free image resources listed at Smartcopying
Information from Smartcopying on using music, including a list of free music sites
Open Education Resources are teaching and learning resources available under legally recognised open licences. They are free for people to reuse, revise, remix, and redistribute (depending on the licence type). Many utilise Creative Commons licences.
Information from Smartcopying about OER resources
More free video resources listed at SmartCopying
Creative Commons, Australia (2012), What are the Creative Commons licences? factsheet, accessed from: http://creativecommons.org.au/weblog/entry/244
ImageCodr: HTML code for Flickr images
Smartcopy page explaining about Creative Commons