The point he's making is that Hawking radiation occurs faster for smaller black holes. This means that a smallish black hole would decay too quickly to keep existing, even if it had a constant supply of mass to guzzle. Personally I didn't know that Hawking radiation is so fast...
If a black hole of low mass (a few thousand kg or something) was close enough to a planet, would it just suck in mass from the planet and become even more massive, and thus increase it's event horizon radius and increase it's range of devouring more mass and growing even more? That sounds too badass.
No? Does the gravity of the moon suck up Earth? :\