The undergrad professor (John Gurley) who introduced me to economics was a Marxist. I later took his Marxist econ class, and my copy of Das Kapital was almost pure yellow as I highlighted the hell out of it, struggling to understand what it meant.
The above lecture would have cleared up some of my confusion. It focuses on three of Marx's ideas:
1. The enemy of being is having.
2. From each according to his or her ability; to each according to his or her needs.
3. The point of philosophy is to change the world.