Copyrighted materials are prohibited from use in pitch videos. Avoid using music, images, video or any other content that you don't have the rights to use.
Using copyrighted material can lead to your project being hidden from public view at the request of the copyright holder. We are required to comply with copyright requests in accordance with the Digital Millenium Copyright Act of 1998.
The best way to avoid any issues with copyright disputes is to use content that is free for public use. Look for creative commons licensed materials on sites like Soundcloud or the Free Music Archive.
You can find more information on what is considered fair use of copyrighted materials here.