I’d like to point out that “royalty free” is not the same as “public domain” (or CC0),
so please make sure to check the licences when using any music from ‘royalty free’ sites.
In many cases you still have to provide credit to the author to properly adhere to the licence.
I don’t say this just to be pedantic, people have given up their own time to create this music,
the least they deserve is a bit of credit.
(If you don’t want to give credit, you can usually buy the right to not have to provide attribution.)
(Note - he says ‘Creative Commons’ but appears to mean ‘CC BY-SA’ going by the logo on the left hand side.)
(Most music is CC BY, which is similar to the Apache 2.0 licence for code,
i.e. you can change it as much as you like,
but you must provide a copyright notice to say who the original author is,
and you must indicate if any changes were made.)