In the United States, upon creation every creative work is automatically copyrighted. And it’s untested law whether you can actually abandon a copyright into the public domain in the United States, much less everywhere else. So the statement that it “should” be “[f]ree of copyright restrictions” is inherently problematic.
Instead, what’s sometimes done is to dedicate it to the public domain, and in case that doesn’t work, also release it under a very permissive licence. (That’s what Creative Commons’ CC0 licence does.) The first case is “[f]ree of copyright restrictions” (if legal to do so), the second case is essentially the most lenient copyright restriction imaginable (if the first case is legally invalid).
But the other Creative Commons licences are copyright restrictions in every sense. The foundation of those licences’ restrictions is copyright law itself. Given that, FIRST shouldn’t say “[f]ree of copyright restrictions” when they intend to permit CC-licenced works.
Incidentally, the statements “If using copyrighted music must have written permission” and “If using Creative Commons Music (CCM) on line, the music must be used in accordance with the appropriate license and properly attributed.” are redundant. A Creative Commons licence is written permission. And why is “on line” use different from other use—and what does that even mean?
To do what’s required by the law, and what’s required for FIRST, I’d recommend you select from works for which commercial re-use and derivative works are permitted (e.g. CC BY, CC0 and public domain works1), and just attribute everything (even when not required by copyright law) in the credits. This also helps avoid any plagiarism concerns—which are essentially distinct from copyright ones.
Among Creative Commons licences, you may want to avoid the SA (share alike) ones—because they’re a huge copyright restriction.2 Also, the ND (no derivatives) licences should be avoided, unless you are planning on re-using the entire licenced work without changes. The NC (non-commercial) ones are a toss-up: you’ve got no commercial purpose, and FIRST hasn’t stated one, but it’s still technically a restriction that might affect their sponsors’ ability to use the video. Creative Commons also has a lot of other, strange licences, which probably won’t be relevant.
Then, ask in the Q&A for an explanation of whether FIRST requires copies of the “written permission”, and in what format, and by what deadline (if any).
In any event, FIRST ought to realize that “written permission” is only as good as the knowledge, belief and honesty of the person who wrote it. It’s not a total bar to legal action, and hopefully FIRST is willing to accept that risk, based on your due diligence.
Aside: Since it’s pertinent to the topic at hand, using “should” and “may” to mean “must” and “may only” is bad form for a specification. Is there a mandatory part and an advisory part of that section of the manual? Where does one end and the other begin?
1 By this I mean stuff that has ended up in the public domain due to age or some other reason, and stuff that the author has attempted to release into the public domain. In the decades that copyright law has existed, the fact that there’s no definitive answer about the legality of declaring something in the public domain is good enough for me to assume here—given the low stakes—that it’s a valid release, or at least a binding prima facie covenant not to sue.
2 These are tricky: they impose the same licence conditions on all downstream users of the content, by requiring you to apply a similar licence to your work. There’s some controversy about which portions of derivative works are ‘infected’ by those terms, and whether the lack of legal authority to do so is a bar to re-use.