Yes, this Kml specification allows this, you just use relative paths.
However, your problem is really related to security restrictions in certain applications for certain types of content.
For example, the full Google Earth client allows you to load Flash (swf) content into balloons while the Goggle Earth plugin does not work. The same goes for iFramed content, etc.
Thus, the answer to the question depends entirely on which application you are viewing in Kml / kmz, and has nothing to do with the Kml or Kmz specification.
source
share