According to physics there is heat, electricity, magnetism, electromagnetism and kinetic energy.
These are simply different manifestations of the same one energy.
So I ask you again: Which of those are the pyramids supposed to harvest?
I'm speculating here (as I haven't studied pyramids extensively), but I can imagine that certain geometric configurations might have non-local effects on distribution of energy within certain regions of space (either inside of the pyramid or somewhere outside). As a result it might have certain effects on consciousness of the people within those regions of space (either inside or some place outside). The rejuvenation temple comes to mind as an example, but I'm not sure pyramids were designed for that exact purpose.
So again it's not that they were necessarily built to harvest energy per se, but more likely to focus energy in a certain way to have certain effects. And if you are tempted to ask again what kind of energy, then my answer would be "The Field Energy", the one that permeates everything and the one we are all made of. Think of it as a stem-cell energy which can take any form depending on the geometry it traverses. Even in modern particle physics scientists observe phenomena of one type of "particles" decaying into another type of "particles", so those types of energy (heat, electricity, magnetism, electromagnetism and kinetic energy) that you mentioned are not intrinsic to themselves.
Oh btw: Are you trolling? That yt video seems way, way farther out than your usual posting style, can it be you brought that up just because I called you new age?
The right part of my brain (a quantum part) triggered a pattern recognition scheme and highlighted that particular video as fitting for the conversation content-wise, however the left part of my brain (a sequential part) recognized the form of the presentation as way too unusual for the population of this board to conceive and advised to proceed with caution. I then made the decision to proceed with posting and study the effects it would cause, as by not doing so I would have achieved nothing. So, yes, I like to troll at times
Here is another video that shows how interconnected everything is.
http://www.youtube.com/watch?v=N4mDcvOsBDYThis time it discusses several scientific experiments that are being conducted at present time and touches upon topics of non-local effects related with frequency, vibrations and energy. We are making a very good progress in this area and maybe at some point our civilization will be able to comprehend the mystery of the pyramids and their purpose.