No idea honestly. I would say they want us to use only music from SC, since any non-copyrighted music could be copyrighted in the future.
I’m also wondering where could we get the SC soundtrack. Do we have to buy it, or can we get a song from Youtube?
This portion was specifically created to avoid copyright issues. It makes it impossible for us to highlight the video on official channels if it contains copyrighted materials. The safest bet is to use our official music or music you have created for the commercial.