Plugin Detection, Redirects, and Proper Indexing

[jmatthew3]

Hello, I'm working on a site that displays video in various formats and bitrates to users, remembering their preferences via a cookie.

If the cookie isn't set, they get 301 redirected to a page that lets them choose bandwidth & video format (real vs. windows).

All "video player" pages are linked to directly on the site, so that's what a spider would find. however, when a search engine gets there, it will get redirected to a page w/o any content, just a small form.

What's the best way to *not* redirect google, but still redirect the users we want redirected?

I'm thinking of doing a 301, but checking user-agent for the various search spiders and not redirecting those, but i'm worried about a penalty.

thanks!