Well, I can't watch that video in my country due to copyright protection.
I think open mindedness is to accept everything that is going on in mind, without resisting or pushing anything away.
These processes in mind are just dependent arisen and impersonal, but if we start to take them personal and clinging starts, closed mind already happens. My two cents.
"An important term for meditative absorption is samadhi. We often translate that as concentration, but that can suggest a certain stiffness. Perhaps unification is a better rendition, as samadhi means to bring together. Deep samadhi isn't at all stiff. It's a process of letting go of other things and coming to a unified experience." -