quick question about the payment of "dividends"

If the dividend is paid in ETH to the wallet that they were purchased from, then what happens when one buys or sells a token from the exchange?

do ICO holders still get dividends even after the tokens have been sold on or is the dividend paid into the ETH address that the token currently resides on? if it is all automatic then how does the smart contract know which address to send ETH to?

If the bonus forever goes to the ICO address then its great for the current investors but it would make CTX less attractive on the exchange where the true market price will be established.