That was really awesome of you to go the distance to try and help me out like that, I really appreciate that. However, in my case it was a different problem. Before I posted the video, I double checked all my smooth settings one by one. Check marking the "Smooth All" option fixed it. I was pretty sure I tried all the smooth options before but must have skipped that one. "Smooth Internal" and "Do Not Smooth" options result in the seam but the "smooth all" option eliminates it. Nonetheless, I'll keep in mind that extra vertices can cause it too.


Edit: Here's what the issue was
YouTube - GlassUvMapping