Is energy always conserved?

Excellent presentation, but this really begs for an in-depth discussion about what the laws of physics (in general) really are and what exactly that law of conservation of energy really says.  Maybe too abstract for this venue, but you could do a Feynman challenge and prove that you understand it by explaining it in terms that a reasonable person can understand.  He failed this challenge (in his view) regarding his own understanding of quantum mechanics, thus leading him to claim that no one understands it.