An alternative to using copyrighted images, music or video for your projects is to use “copyleft” works, more specifically those licensed under Creative Commons. Creative Commons is a nonprofit organization that creates tools to allow creators of online digital content to control and promote the use of their work. Generally, images or music with a Creative Commons license are available for you to use for free, sometimes with certain guidelines (for example: attribution, no modification allowed, non-commercial use). Of course, you can also designate your creations under the Creative Commons (See the different types of licenses available here).
Below is a list of websites from which you can source for images and music that have a Creative Commons license: