Link colors don't work. Given this, you cannot easily see where you've been and which links you've yet to visit. This lack of orientation creates navigational confusion. Sure, this can also be true. Users are thus forced to read text in the designer-specified font size, which is almost always too small since designers tend to have excellent vision.
Flash reduces accessibility for users with disabilities.
I'm not informed enough to understand how this is true. I wish Nielsen had elaborated to explain how this issue relates to Flash development. The 'Find in page' feature does not work. In general, Flash integrates poorly with search. Internationalization and localization is complicated.