No he didn't came from India. He is born in New Orleans, USA. But point holds, there is awful teachers all around the world, including USA, and a vast collection of good quality instruction videos is valuable.
I'm from Finland, which tops in PISA rankings and what I've read about the reasons behind our good PISA performance, one is that teachers profession is still valued here, we have quality applicants and thus good teachers compared to many other countries.
Based on that experience, I'd say that Sal Khan is definitely above an average as a teacher. Anecdotally I'd say he is a very good teacher, but that's debatable.