So of course it's not actually Bart, but Nancy Cartwright, the woman who provides his voice. She and a bunch of other people you've never heard of are talking about some crazy Scientology stuff. Cartwright is the real draw here (she's at 1:01 if you want to skip ahead, close your eyes, and pretend), but the “Jewish” woman is also amazing throughout. Oh my god, I get verklempt.
http://www.entertonement.com/clips/64689/Bart-Simpson-Sci...
Actress Nancy Cartwright’s affiliation with Scientology has escaped public notice for the most part, but those days could be over. Cartwright, the voice of Bart on The Simpsons, is featured on a robo-call announcing a church event, the Village Voice reports. The actress peppers the invitation to the “Mecca of technical perfection” with her Bart Simpson voice and trademark laugh.