Does the one who joins the prayer late have the right to say the closing salam with the imam if he forgets and adds a unit of prayer?

The questioner : Hello, yes, a question over the phone. Yes, he says: A man caught up with the imam for one unit of prayer, but the imam made a mistake and added an extra unit. What is the ruling in that case, O Shaykh?

The Shaykh : The ruling is that he follows the imam? And if the prayer of the one who joined late is completed, he says the closing salam with the imam. For example, if he missed one unit and the imam prayed five units out of forgetfulness, he says the closing salam with the imam and his prayer is valid.