I was once at Ultimate Airsoft and had a similar situation. A guy was proned next to a wall that was made out of this translucent, semi-transparent plastic material and shooting on the right side of it with just his gun and helmet sticking out. You could see outlines in the plastic, but only if you were moving or wearing a dark shade since it was white tinted. I was returning to spawn and was approaching him on the left, and told him to stop shooting because he couldn't/didn't see me, and couldn't hear me either, and i don't want to get shot in the ankle because that shit hurts (implying that people were trying to shoot back at him, i would be directly in the line of fire).
Now here's where it's different. The guy was peaking in and out and taking pot shots when he wasn't looking outwards. He would acquire target, go back behind the wall, and keep shooting. Dick move. I wanted to step on his gun because he wouldn't stop shooting, and wanted to avoid going over him (again, people might have been shooting at him, don't want to get shot again while respawning). I ended up doing just that and afterwards, had to tell him to get up and stop doing that shit because it's considered blind firing, he wasn't listening and getting shot point blank in the ankle hurts.
If he's actively looking and shooting, I suppose this isn't a case of blind fire. If he's acquiring targets, and shooting with just his gun sticking out without revealing himself, then that's blind firing. Without an alternative angle to see where the person is facing and positioned, I can't say with certainty that the scenario such as the one in the video constitutes as blind firing.