Look for discussion with British journalist Andrew Marr during a BBC interview in 1996.
The lead in to the quote starts at https://youtu.be/GjENnyQupow?t=662
"I don't say you're self-censoring - I'm sure you believe everything you're saying; but what I'm saying is, if you believed something different, you wouldn't be sitting where you're sitting." -- Noam Chomksy to Andrew Marr