The footage shows the gang throwing stones, breaking glass and chanting in Saft al-Kharsah village in Beni Suef Province, near Cairo.
The incident is said to have happened on 22nd July but the video has only just been posted online.
Rumours that a man's home was being turned into a church were said to have angered the Muslims who decided to attack the village.
The crowd gathered after prayers and began hurling rocks at the houses.
اعتداء المسلمين علي المسيحين في مركز الفشن محافظة بني سويف
— علماني مصري (@Human_Secular) July 22, 2016
A mob of Muslim assaults on Christians homes with stones pic.twitter.com/0sJ8YmGCY7
Footage taken from the balcony of one of the buildings shows children crying as the mob advances down the street.
Police cordoned off the area and held a 'reconciliation meeting' where the Christians stressed they were not building a new church.
Eighteen people were arrested.
Mervyn Thomas, Chief Executive of Christian Solidarity Worldwide (CSW) said: "The video footage of the attack in Saft al-Kharsah is a disturbing and stark illustration of the unacceptable sectarian violence endured by Coptic villagers in Upper Egypt on an increasingly regular basis.
"We continue to call for the perpetrators of such violence to face criminal proceedings, as reconciliation sessions have done nothing to stem the frequency of these attacks."
