(he gives charity to this man and prays with him): Does it not indicate a second congregation?

The Shaykh : From his saying (peace be upon him): .
The student : Come forward, come forward.

The Shaykh This is his wording, whereas if he had said to him: What is the difference between the two expressions?
The student : That he be an imam for them.

The Shaykh : He was not an imam for them, no.
The student: Yes.

The Shaykh : So who was the imam then?
The student : The one who has prayed the obligatory prayer, meaning the one who has prayed the fard.

The Shaykh : Well done. After these three clarifications, a group of those who had missed the first congregational prayer entered. Among them were those who had prayed the obligatory prayer, those who were praying voluntary prayers, the one giving charity, and the one receiving charity.
The student : ... .

The Shaykh : Hmm. So many scholars include this hadith in the topic of repeating the congregational obligatory prayer, but that is not the case. Rather, it is... So, whoever has prayed the obligatory prayer may pray voluntary prayers behind the one who has prayed the obligatory prayer. He may pray voluntary prayers behind the one who has prayed the obligatory prayer. This is the indication of the hadith, and nothing more.