Airport Videos on Google Earth
PlanePlaces are the only other site that I have found so far that has started producing KML files that embed videos on Google Earth. They have produced a file of Airport Videos that has over 2800 videos of airports around the world.
The file was created by running a ICAO airport identifier search against the YouTube API. As such, it's subject to errors but they have included e-mail alerting within the Google Earth balloons so the file should become more accurate the more it is used and viewed.