futurebird , 
What kind of entertainment are "Let's Play" series?
It's a bit like a reality show, a bit like a how to program, a bit like a role playing game.
Role Playing games are under-appreciated as art forms because they can't be easily mass distributed. I call them "collaborative story telling"
The "Let's Play" is even more alien to the people who study great literature and movies.
But they still should be engaged with as art, analyzed like art, valued like art. (preserved for history like art)