Any components below a script aren't downloaded until after the script is loaded, regardless of hostname. This page contains:

• two images: one from stevesouders.com and another from sowrock.com
• a script from stevesouders.com that takes 10 seconds to load
• two images: one from stevesouders.com and another from sowrock.com

The first two images are downloaded, but even though the browser supports downloading two or more components per hostname in parallel, the latter two images aren't downloaded until after the script is done loading.

The <SCRIPT SRC="..."> tag is here.

Once you see this text it means the script is done loading. Now these latter images are downloaded.