Well, I keep calling them "sails" but the more technical term is probably "drive grids." The general idea is that they capture and focus the spatial distortion from the FTL drive, possibly as a means of increasing navigational accuracy. However, these probably won't appear on many other ship designs, if any, so they may have been a one-off tech innovation that proved impractical on other ship classes or something like that.
As for the dislike on YouTube, ehh, whatever. Some people have nothing better to do. It's really just a rigging test anyway, so I'm not gonna lose any sleep over it.