Why does this start with "why would you" not "why are you" or "why did you"? I want to know the difference, thank you 😆
"Would" here is used to expresses what someone was willing to do in the past. Even though Chandler is smoking in this scene, the speaker assumes that he has been smoking in the recent past as well (after not smoking for a long time), and is questioning his willingness in the past to start smoking again. That is why she uses "would you" rather than "are you" (which is present tense) and "did you" (which is past tense, but does not express willingness to do something).