Video: KVM Architecture Overview
I downloaded all of the videos offered from the Red Hat Virtual Experience 2009. They made them available as Ogg Theora .ogv files so I didn't even have to convert them. They are of moderate to low quality especially with regards to audio... so they can be a little annoying but the presentation material is generally top notch.
In this video, Andrew Cathrow of Red Hat spends about 23 minute explaining what KVM.