Although, Google introduced a feature called "first click free" to protect your content while allowing you to include it in Google’s search index. Some sites continue to get their contents indexed with Google, and ask for registration, when a user clicks the search results and visits the page. This is especially annoying, because these site increases the number of page views.
To view such contents, one workaround is to copy the URL of the page you can't access directly in Google's search box and click on the first result. If Google didn't index the page, you can use SearchWiki to add the page in the list of search results: make sure you are logged in using your Google account and click on "Add a result" at the bottom of Google's search results page. Another option would be to use the credentials collected by BugMeNot. Or finally, report the site links to Google.
Source:→ Google OS