I only watched a few seconds but I assume he is talking about something along the lines of the buddhist concept of “no-self.” The belief is that one is not composed of any permanent essence - what we identify as “self” is only a passing phenomena whose temporary nature is the effect of some other cause. Because what we are is not permanent and also not its own thing (because of its dependent origination on other phenomena), it is not even possible to precisely identify the self - such a thing doesn’t exist. It is a conceptualization which blinds us to the true nature of reality, which is that of infinitely interconnected phenomena - or, conversely, a single infinite phenomenon (the distinction itself probably being considered a misleading conceptualization).

I’ll cut the lecture there, but obviously there is more to the concept and its importance to buddhism in the context of other concepts. It didn’t seem like the guy was really intent on educating anyone anyway.