In this video Sheikh ibn 'Othaymneen gave a fatwa about the case of a mu'addhin who performs the iqamah and would start the payer if the regular imam wouldn't appear within the time frame defined by the ministry of religious affairs in the given country.
And after clarifying that both imam and mu'addhin have a certain role in the prayer and none has the permission to exceed his predefined role and its limits. Then he says: that in case this mu'addhin did so without the permission of the imam this is haram and some scholars would consider this prayer in congregation as invalid.
As he didn't elaborate on whom these scholars are.
I'd like to know who are those scholars who may consider a prayer invalid if a person lead it without the permission of the regular imam or for example if guest lead a prayer without the permission of his host based on the sahih hadith:
The Messenger of Allah (ﷺ) said to us: The one who is well grounded in Allah's Book and is distinguished among them in recitation should act as; Imam for the people. and if they are equally versed in reciting it, then the one who has most knowledge regarding Sunnah; if they are equal regarding the Sunnah, then the earliest one to emigrate; If they emigrated at the same time, then the oldest one in age. No man must lead another in prayer in latter's house or where (the latter) has authority, or sit in his place of honour in his house, except that he gives you permission or with his permission. (Sahih Muslim)