"I might add..." is a colloquialism; it's something that is said less formally. He meant "you should add..." (or "I might add if I were in your place".) It's a

"I might add..." is a colloquialism; it's something that is said less formally. He meant "you should add..." (or "I might add if I were in your place".) It's a way of saying the same thing, but for non-native speakers it is a bit unusual.