Mains input protection: MOVs, Caps and Chokes, Oh my?!

[Jebnor]

I'm wondering about mains input protection.

In EEVblog #268 at about 5m30s http://youtu.be/27c4RTntAPw?t=5m30s there is a great view of all the mains input components.  I understand that the Vantrex unit is a high end unit with tight margins and is overkill for any little projects I may have, but could someone explain or provide reference to what the components do and possibly, how to select them?

My understanding is this so far:
MOVs -- Metal Oxide Varistors: Protect equipment from high voltage short term transients.
Capacitors -- I know what they do, in DC mostly.  Why do they help on Mains inputs? just Transients again?
Chokes --  common mode chokes on Mains input.  This one I don't understand at all really.  Common mode means they are on the same core right? Does that help with phase alignment of the Mains current or something?

References to Lectures, PDF, white papers, application notes and other sources where people know their stuff are accepted freely. 

[c4757p]

Chokes --  common mode chokes on Mains input.  This one I don't understand at all really.  Common mode means they are on the same core right? Does that help with phase alignment of the Mains current or something?

The choke is not protection, it's for filtering. Common mode refers to the same polarity, not the same core (though they are on the same core; a CM choke is just a special transformer) - current flowing in the same direction on both sides, so the return path for the current is elsewhere. RF emissions, mostly. The point of the choke isn't even to protect your circuit from noise on the mains, as many beginners assume, but to protect the mains from noise from your circuit (and avoid turning all the wires in your house into SMPS switching frequency transmitter antennas).