I've just been lurking, but I think that if you saw it on the video, you picked one frame and ignored a bunch of other ones.
I did a screen capture of the video at a few points, to show that the injury mysteriously moves...
at 1:03, there's no obvious gash in his head, at least none that I see...
at 1:04, there's two black dots.
at 1:05, there's a vertical black line, probably close to the same frame as the admittedly doctored image (I wasn't able to pause the video to get a screen cap). There's a a black cross, which quickly becomes a horizontal black line
at 1:06, the black cross is back, but the horizontal part seems to have moved further up his head!
by 1:08, it appears to be gone (I've hit the limit of 5 attachments)
That is one magic gash!
Can you do any screen caps which consistently show the same scar?