I was looking at the OP again, at the photo collage specifically, and noticed the second image from the left, on the second row from the top. This one shows a remarkably smooth curve. When reviewing the video again, at this specific moment, I noticed it has something on the left, looking like tree branches or something.
Now I understand what you mean by remarkably smooth. The top of the hoop is reflecting the light source as a mirror would (a specular reflection), and it's over-exposed. So it looks like a featureless glow.
There's a large (in relation the size of the object) nick on the left. The fine groove on the side of the bangle is very visible in this one..
We'll call this a hoop.
White arrows - A groove in side of the hoop.
Green arrow - a nick the hoop.
Green arrows - far edge of the top of the hoop.
Blue arrows - near edge of the top of the hoop.
Red arrows - the lower edge of the hoop where it meets the wooden dowel
Probably the same nick in the same hoop, but the hoop is placed differently.
I'm sorry. I should have explained this one before. Yalcin videoed a lot of different things.
A little further in the video, this expands until it almost full obscures the illuminated curve.
I still have no idea he was filming, but the artefacts seen later in the videos are likely obscurations of the (original?) illuminated curve, so I am not convinced about it being bracelets or tvs or whatnot. I think it something much more easy and obvious.
LIVE VIDEO (not a screenshot)
In this case - where you have this video cued up - these are distant lights, probably offshore on a boat. (There's a later shot of something that's definitely a boat, so...)
I can't be sure, but I think it's a small cabin cruiser at night, offshore of the Yeni Kent Apartments, probably fairly distant. I don't think it's down shore, or you would see ground lights. I think it's out offshore.
Something like this.
Or more likely an inboard like this one; with a smooth transom.
Blue arrow - navigation light on the bow.
Green arrow - lights in the windows of the cabin
Red arrow - light illuminating the surface of the transom (flat part on rear of boat)
Not certain of this one. But when you watch the video I think that's what it is. There are times when the windows are pretty clearly windows. In any case, they're just distant lights. No mystery.
By "illuminating the surface of the transom," I mean the way a license plate is illuminated. A splotch of light, not a distinct light source.
All these are from that same video.
These are lights on a distant cargo ship, on a misty early morning.
The landing lights of a distant aircraft.
This one I'm confident of. It's a boat; and I think it's closer to shore than the first one. The blue line is an LED strip on the boat.
At 43:50 Yalcin finally stops playing with the camera and let's it sit still on the tripod. At that time you can see the boat rocking gently on the waves. I'm not sure what the sparkly lights are. I think they're specular reflections of the LEDs on wavelets.
LIVE VIDEO (not a screenshot)
Lights on a ship, invisible in the mist and dim light. I think there are two lights and an inferior mirage of the same.
I just realized what this probably is. There's a green light on the left and a red light on the right which means these are navigation lights on the bow. And a flashing red masthead light in the middle, which means it's bow on to us, (facing us). And there's a bright mass of lights off the starboard side. It's a squid boat.