UPDATE: This problem was swiftly addressed by Netflix.
Safari 5.0 has been out for about a day, and some people have found that a few websites do not work properly with the new version. One highly used site that is having problems is Netflix, where the streaming video feature has stopped working for people who have upgraded.
When clicking the "Play" button for a streamed video, the website will give an error claiming streaming is not supported on the current browser, and will then list the system requirements which include "Safari 3.0 or higher." The streaming video on Netflix requires Silverlight, so people who have noticed this problem have tried to reinstall the plugin under the assumption that the plugin may be causing issues; however, this has not helped the situation.
The fix for this problem is to change the user agent for Safari when loading the Netflix website. The user agent is the identifying string that your browser sends to a web server, which can help the server supply a specific version or set of features of the website that are tailored for the browser and operating system being used. Many browsers including Safari can change the user agent for testing and compatibility purposes.
It seems Netflix has not updated their website to recognize the user agent string for Safari 5.0, but by changing the user agent to version 4.1 you should be able to get streaming to work.
- Enable the Developer menu by checking the box to do so in Safari's "Advanced" preferences
- Choose "Safari 4.1 -- Mac" from the "Develop" → "User Agent" menu
- Log out and log back into Netflix.
After this procedure is done, you should be able to stream the videos again.
While the ability to change the user agent is beneficial and works in this situation, unfortunately you cannot assign a specific user agent string to be used for a given website. Therefore you will either have to keep the user agent as the old version, or change it every time you wish to use Netflix's streaming options.