a. make sure you are logged into Twitter.

b. search for [vevo]. http://twitter.com/#search?q=vevo

c. second Top Tweet as of 16:10 PST is a protected tweet: http://twitter.com/gagadaily/status/15721434645

This demonstrates a case where random user can view the content of a Protected Tweet.

In this case it seems the Retweet is making something private into something public.