@Aphoric,
What Heidegger means by Dasein is more often than not dependent upon the context in which it is discussed. And it is Heidegger's way to let the meaning of a word or concept gradually unfold and deepen to the reader as he thinks through the work alongside the philosopher, so it is difficult to provide ONE meaning for Dasein (as if it necessarily needs to have ONE definition).
It would be hard to comment on a commentary without knowing its title or author, especially when he begins to discuss something like "pop culture" in relation to Heidegger's writings.
Every philosopher attempts to give an account of the world, and his positions add yet another perspective (or, way of seeing or way of looking at the world). When we learn to see it, in a thoughtful and sympathetic way, from a viewpoint different from our own (limited and dependent upon our own situation), our normal world changes in subtle ways, becoming more problematic and deeper than before. We should not be dismissive of other thinking, nor cling to preconceptions, for that is ignor-ance.
"Convictions are prisons."
Regards,
John