Earlier quoted context omitted.
I hadn't actually heard of it either, from one of the first results: > This whole thing got started earlier this month, at the Talladega Superspeedway. Brandon Brown had just won a NASCAR race. And sportscaster Kelli Stavast at one point commented during an interview with Brown afterward how the crowd seemed to be chanting in his honor: ‘Let’s go, Brandon!” >Unfortunately, that’s not actually what they were chanting.…
At 0:13 on your video, the crowd is clearly saying "fuck Joe Biden". So this video is explicitly political, given that its name is a dogwhistle for "fuck Joe Biden".
"Dogwhistling" doesn't mean "saying something that means something else", it means using coded or indirect language to communicate something to a specific group of people while hoping that the general audience doesn't pick up on your meaning. Everybody knows what "let's go Brandon" is code for, and the people who say it aren't trying to hide what they really mean.