How does Storyline pre-load content, particularly video?

I have a large SL file with 10 modules (all one SCO). A tester noted accessive load times, particularly in one module. This module contains short, embedded videos on some pages. No video is longer than 1.5 minutes. 

It would be helpful to understand how Storyline handles the preload of data for each page, particularly ones containing video.

• Is page content preloaded in its entirety? Is it page by page, scene by scene, or how?
• Would pages with longer video segments load faster with compression added?
• What are things to be aware of when faced with long load times--does the overall size of the SCO impact this?

Thanks in advance for your responses.