I saw that length difference too.
Regarding Silverlight, I did some testing and it would seem that if IE7 is run with administrator privileges, Sliverlight will run, I can watch the video at On10. However, if the IE7 browser is run without admin privileges (normal operation), Silverlight will not run and the browser/web page doesn't even think Silverlight is installed. This was tested at On10 and from the Microsoft home page.
So, what gives? Why is Silverlight broken? Is there a fix available for this obvious security bug/flaw?