Since updating to this build I haven't been able to use Netflix in Safari. It works without a problem in Firefox or Chrome, but I don't usually use either of these browsers. In June there was a user who posed the same question with 10.11.1 beta 5, and he/she solved the problem via clearing history and all data, but this did not work here.
Netflix describes this problem as coming from a lack of HTML 5 support, although HBO go and other video continue to work without any problems (its just Netflix and just after this update).
This is a Macbook Pro Early 2011. I've submitted an error report with Safari and OS diagnostics. The build I'm running is 15B22c. I've noted no other problems with video, audio, or performance.
Suggestions?
