Stop the video right at 1:19.  Now clip the lines after the point at which they converge at the tip of the pyramid.  That's where the sun would be on a flat earth model.

Or, perhaps better, stop it at 1:46.  At the tip of the pyramid, before the lines pass through each other and diverge into space, that's where the sun would be.  There are a handful of extraneous lines around the edges, but that could actually be explained as reflection off the dome.

.
If you pay attention (for a change) you'd notice that none of the vectors touch each other.
So there isn't any place where they "converge."
Each vector represents an independent direction towards the sun and no two of them are looking in the same direction using the "flat" earth model, so they don't "converge."  Use a globe model, however, and they ALL are looking in the same direction!
That's the point, which you somehow manage to miss again and again.
.
There is no "pyramid" at 1:46.
The vectors do not "pass through each other."
Your perception is all twisted. No wonder you have a problem understanding reality.