As much as I like to laugh at poorly trained ICE officers, it really looks like this is a rifle mounted tactical light that flashed on, not a muzzle flash.

There are two reasons why I say that:

1: If you freeze frame you will see that there is no “ball” of light floating in front of the muzzle. It is the snow in the ground reflecting the light

2: Still on the freeze frame there is a white steak near the muzzle that is caused by a source of light that moved quickly with the rifle. That’s the tactical light. The majority of a muzzle flash happens a few inches in front of the muzzle and it doesn’t last long enough to cause streaking on camera like that. There is something known as muzzle glow as well that happens directly at the muzzle but it would have been washed out by the muzzle and once again it would have not lasted long enough to create a streak on camera like that. It wouldn’t be white either, but orange-red.

The snow being kicked across the ice by their feet really looks like a puff of smoke too upon first glance which further makes it erroneously look like it was the rifle that went off.