Memory, the history of the present, includes forgetting
According to Pierra Nora, memory creates social identities, unites communities, and it, be our consciousness of the past, can be the symptom of the disappearance of ceratin living traditions. It can be seen that memory provides us a field where past and present can paradoxically exist at the same time, while memory in the present world works as a historical trace and exist as a simulation of the past, mordern societies can reenact them through different rituals, then memory may also be the history of the present. This actually described and born with our inability to live within the real memory, and our desire to present what is no longer exist because the real environments of memory indeed disapeared. But bear in mind, memory with the construction like this(e.g. social relations) can be altered at any moment, even for personal or social circumstances. Memory is produced through discourse, though when what is to be remembered(preferred) and forgotten are not decided by us, it gives the controller(of the memory) power to create discourse, and the authenticity of the past somehow shape the discourse of present.
The video may seems confusing, but it supposed so. It should deliver the confusion of the scenario, inability to realize the past and present because we are doing it at the same time. Meanwhile, it seems that somebody has chose what to prefer or remember in our memories, it is unreliable, because on top of that, memory itself alters constantly. Then, our reality is too, unreliable, because our acknowledgement of the reality is based on our experience and knowledge of/from the past, and so it may alters along.