Ah now this makes sense!  I guess it helps their time modeling on the progression and how they form:

“It might sound contradictory, but finding such a small, large black hole is very important. We can use observations of the lightest supermassive black holes to better understand how black holes of different sizes grow,” said Dr Vivienne Baldassare from the University of Michigan, lead author of a paper accepted for publication in the Astrophysical Journal Letters (arXiv.org preprint).

And here is a related mini documentary on black holes in general:

A black hole is a mathematically defined region of spacetime exhibiting such a strong gravitational pull that no particle or electromagnetic radiation can escape from it.[1] The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole.[2] The boundary of the region from which no escape is possible is called the event horizon. Although crossing the event horizon has enormous effect on the fate of the object crossing it, it appears to have no locally detectable features. In many ways a black hole acts like an ideal black body, as it reflects no light.[3][4] Moreover, quantum field theory in curved spacetime predicts that event horizons emit Hawking radiation, with the same spectrum as a black body of a temperature inversely proportional to its mass. This temperature is on the order of billionths of a kelvin for black holes of stellar mass, making it essentially impossible to observe.

We hope you enjoy the video!

thanks to sci-news.com for the great info

thanks to NASA for the pic