This interview is included on the Criterion Collection DVD, uploaded here from YouTube.
In response to the perspectives on g/God or who g/God is within Bergman's so-called trilogy, here's my very brief take:
In Through a Glass Darkly god is an illusion encountered by the emotionally unstable (consider for example that only Karin "sees" god). In Winter Light, god is a projection of one's neurotic (Märta's attraction to Pastor Ericsson) or pathological (Pastor Ericsson's understanding of god after his spouse passes away) desire for someone else. In The Silence: god is a projection of one's own desire, whether sensual/emotional (Anna) or logical/intellectual (Ester). In sum, God is silent/does not exist because either the film's characters are sane, they project the idea of God onto others and others are silent, or because their idea of God is tantamount to their own behaviors and they find silence when they are alone. I think there is a two-hour lecture embedded in this summary :), but that's the gist of it.