alt Hacker NewsSpace and the enormity of it breaks your mind when you start thinking about it.
The star in the middle of the animation, is approximately 20AU (Astronomical Units) in size looking at the scale line. 20AU is approximately 1.8b miles/3b kilometres or approximately the distance from the Sun to Uranus.
If Google's correct, if everyone on Earth lived on that star - each and every one of us could have a backyard larger than the surface area of Earth ;p
I don't think you should infer the radius of the star from the blacked out region. I think they just do that because the luminosity of the star is so intense it would blow away the sensitivity needed to see the planets. So they set everything to zero for a certain zone on the lens/sensor. It's not the physical surface of the star.