The meaning of Al- Salafiyah

What is the meaning of "Al-Salafiyah"? And to whom are they attributed? And is it permissible to deviate from the understanding of the Righteous Predecessors (Salaf) in the explanation of Religious Texts? (00:06:30) 

He answered: 
I will say a true word after which no Muslim can argue, after the truth becomes clear to him.

    First of all, the Salafee da'wah is an ascription to what? 'Salafee' is an ascription to the 'Salaf' (the pious predecessors), so we have to know who the Salaf are when scholars of Islam refer to 'Al-Salaf', and then what this ascription means and its importance in regards to its meaning and implication. 

The Salaf are the people of the first three generations whom the Messenger of Allah (Salah Allah 'Alayhi wa Salam) declared to be good and rigteous, in the authentic and mutawaatir hadith narrated by al-Bukhaari, Muslim, and others through a group of the Companions that he [i.e. Prophet Muhammad] said: "The best of people are my generation, then those who come after them, then those who come after them.".
     These first three generations that Prophet Muhammad testified that they are good and righteous are the Salaf. So the Salafees attach themselves to the Salaf. After we have known the meaning of 'Salaf' and 'Salafee' then we should bear two things in mind. 

The first: That this ascription and attachment is not to a single person or a few people, as is the case with other Jamaa'ahs (groups) that are present in the Muslim world today. This is not an attachment to a person or even tens of people, but this is an ascription to a group which will not err.
    
       That is because the Righteous Predecessors would never agree upon falsehood, and it is impossible that the Salaf would unite upon an error, as opposed to the Khalaf (the people of later generations). With regard to the later generations, there is no text speaking in their favour, on the contrary, their majority are generally spoken of with ill, such as in the end of the previous hadeeth when he [peace be upon him] said: "Then there will come a people who give witness and their witness is not asked for...", and in another hadith you can see Prophet Muhammad [Peace be upon him] praising a small group of people, but censuring the remaining majority as can be understood when he said: "A Taa'ifah (small group) of my Ummah will not cease to be upon the truth, not being harmed by those who oppose them, until Allah's command comes" or"until the Hour is established".
      So this Prophetic tradition gave praise at the end of times to a specific Taa'ifah, and linguistically, 'Taa'ifah' refers to a small group composed of a single person or more.