Here is a screenshot of the lamp base from the video lecture 107 (left) and a screenshot of my lamp stem (right).
At first I thought this problem is only on my model, but I seem to notice it in the video as well. If you look closely at the edges in the center of the circle from the video and compare it with the proper edges of the circle on my model that I have fixed, you should be able to see that the edges in the video aren’t intersecting properly at the center of the circle. It is very hard to notice, I didn’t find out until I zoomed in on my model, but you can tell that as the edges get closer to the center of a proper circle mesh, they start to mingle together and form this darkened central area, but in the video, you can see that they are unevenly distributed and are not all intersecting at the same central point. I’m not sure what caused this, but I think it has to do with the bezier curve.