From other lectures we know what he means, and in a technically way he is right.
There is no Sunni or Shia.
There is only Islam, which is based on Qur'an and Sunnah.
And those who understood [and lived] the religion best were the Salaf-as-Saleh (Pious Predesccors, which primiarily include the Sahabah,Tabeen and Atbatabeen)
So, a Muslim is someone who follows the Qur'an and the Sunnah according to the understanding of the Salaf-as-Saleh.
That is why there is only truly one Islam, and everything else is really not Islam despite how they despreatly try to cling on the name [Islam] via there sects.
And as much as we dislike labeling people in groups/clans/tribes etc...due to the massive amount of misguidance that sprouted up caused by ignorance, deviance and even some attempts to destroy Islam from within, there needed to be a general name given to those who follow the (correct Islamic) methodology mentioned above, and the name given was Ahlul Sunnah wal Jammah (People of the Sunnah). They are not a 'sect' the way other people who claim to be part of Islam are. It is more a name to make clear the methodology they follow to the layperson and the ignorant so that they will not be fooled by all the deviation and misguidance around them. Otherwise the authentic teachings of Ahlul Sunnah are nothing 'new'. However, the jist of such things is that we avoid falling into sectarianism. You follow the Qur'an and Sunnah [derived from Sahih hadith]with the correct understanding [the understanding of the Salaf-a-Saleh] , you don't have to join a 'group' based on religious or ideological lines.
***Note:Understand that just because he says such things does not in any way mean he encourages unity of theology with them or any other sect in Islam, especially the more extreme ones (such as theirs). Some people have believed this but doing so is taking these words out of context of the light of all his other lectures and statements. He is merely pointing out and answering the issue technically. That if everyone just followed the Qur'an and [Authentic] Sunnah according to those who knew and understood [and lived] it best (Sahabah, Tabeen and Atabatbeen), there would be no need for these categorical divisions.
All the above is Highlighted when he says "Hold on to the Rope of Allah, which is the Qur'an and teachings of the prophet in the Sahih hadith (Aka Sunnah)" which was taken from the source (Prophet), transmitted, further elaborated and acted upon by the Salaf-a-Saleh. In essence its a really simplified version of what I told you above. My explanation went a little in depth because I have seen a lot of people become misguided in this matter thinking that he encourages theological unity with other sects in Islam when in fact, what he is really saying is the opposite, that a true Muslim is one who Holds on to the rope of Allah, and all the factors that doing so entails have been mentioned above. And those who decide to do otherwise and/or bring in innovated teachings are the creators of 'sects' [depending on there differing of their innovated beliefs and methodology], and the 'sect' that goes to Jannah is the original 'sect' [thus not really a 'sect'] and all the others that came after it who insist upon innovation in the religion of Allah [the real sects] are the misguided ones.
Hope This helps InshAllah