I know it’s not a 240 but it is a machine gun that doesn’t require linked ammo. I think trying to determine the type of weapon used from what it sounds like on a YouTube video is dubious at best.
Just now
Shooter tried to blow fuel tanks w/ aviation fuel by the Concert
The article title says “M240 Machine Gun.” No links, no M240. And, yes, sound from a YouTube video is a stupid method of comparison, too.