Kevin MacLeod is musical composer, known for his music being used across the internet. His work is used by YouTubers such as the Yogscast and many others. He has been credited as a composer in over 1,000 films, according to his IMDb page. Macleod is well known for his use of the Creative Commons licensing for downloading his music. Other people can distribute, remix, tweak, and build upon Kevin's work, even to make money, as long as they credit him for the original creation. Other famous sites such as Wikipedia and Wikia also use Creative Commons.
The Yogscast has used Kevin MacLeod's music frequently in their various series. Sips, for example, has used "No Frills Salsa - Alternate" as the intro and outro song for his series, SipsCo. Rythian has used "Darkness is Coming" numerous times in his Blackrock Chronicle series. The original version of Nilesy's Outro Song was sung over Kevin Macleod's "Cipher."