im new to blu-rays and im not sure if this line is normal. it forms half a circle. its not on any other BD.

is it a scratch?

Looks like a scratch to me.

it only appears in the light, its virtually invisible on the surface out of the light.

Logically speaking, it has to be some kind of mechanical abrasion that happened during manufacturing. All optical disks are made of different layers...perhaps it's below the anti-scratch coating or even further down? As long as it plays, I wouldn't be concerned. It won't be getting any worse.

I had this same thing on my blu-ray of Brave. I think it just appeared. Either that, or I just didn't noticed it. I played the movie twice, then it would only play the first 3 minutes or so of the movie before freezing and skipping. I'm going to have to shell out the 8 dollars to get it replaced. I haven't noticed this on any of my other blu-rays. I tried all the traditional scratched disc methods, even rubbing it with toothpaste. Nothing worked. Don't know why it worked before but not now. Oh, well.

Wow, you have tiny hands!

Yeah, it's probably a scratch.

It looks like one that might interfere with playback since it looks like it runs parallel with the data tracks. The data on blu-rays is smaller and denser than it is on DVDs and CDs and even small scratches can affect playback.

Contrary to popular belief, blu-ray discs can be scratched and some brand new blu-rays can come scratched. I've had a couple that look like the scratch is under the anti-scratch coating so it's probably something that happened during the manufacturing process before the coating was applied.

I dunno. All I can think of is the shower scene from Porky's.