Twitch is expanding HTML5 Video Player access to thousands of new users. Their plan is to start with an initial set of users and gradually increase access over the coming months.
If you are selected to be part of the beta test, you will see an alert on the video player letting you know you have access to HTML5.
Since its initial launch to Twitch Turbo users, Twitch has received an enormous amount of detailed and constructive feedback from the beta testers.
Please continue to share your feedback with Twitch, it is the only way that they will hear your voice.
If you have any questions about the HTML5 Video Player make sure to check out the help.twitch.tv guide.
via Twitch Blog