Accelerated web content:

All Text: HTML, markup, and JavaScript
Most Graphics and Photos: includes JPEG and GIF images
Most Banner Ads: including animated GIF images and Macromedia Flash content
MP3 Files, Executables & other files: when downloaded from within your browser
Portions of Games: those that use standard HTTP

Unaccelerated web content:

Streaming media, audio and video files.
Secure pages such as those used for online banking and credit card forms and pages accessed over VPN.
Files downloaded using FTP, outside your browser.
Portions of games that use specialized non-HTTP protocols.