http://youtu.be/xXXxSOhXnPA
Dust and dirt. Mold would be black and in places kinda powdery or slimy if the attic is damp. Your attic looks pretty typical. No worries.
Looks like dirt and cob webs,not mold.
Here is footage of the attic
http://youtu.be/xXXxSOhXnPA