If created in the U.S., it’s a copyrighted work if it is a creative work of authorship fixed in a tangible medium of expression.
I didn’t actually view the allegedly infringing material, so I’m curious: was 1676’s footage original (i.e. the video was a creative work by someone on the team1), or was it a direct copy of FIRST’s feed? Because if it was a direct copy, no matter how much work you put into making that direct copy, no new copyright exists.2
As for the question of whether it’s enforceable in Canada, yes, it probably is, if the copyright holder is willing to bear substantial inconvenience. There actually are international treaties that govern copyright that specify procedures for handling foreign copyrights.
I’m still curious about their intentions, and whether they intended to claim fair use/fair dealing, intended to infringe, or didn’t know one way or another.
1 For completeness: or, was the copyright assigned to the team or its representatives (official or unofficial)?
2 There is, of course, ambiguity about what a direct copy is—but the core consideration is that only creativity can create a copyright.