You are unable to play HTML5 videos in Internet Explorer 11, the HTML5 player displays a black screen only.
A post on the MSDN Blog states: In order to play HTML5 videos in the Internet Zone, you need to use the default settings or make sure the following registry key value 2701 under
HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3 is set to 0.
However, when setting the value of 2701 to 0 in this location the value does not stick and reverts back to 3. Process Monitor showed that Group Policy was setting the value to 0, and then back to 3. Despite putting this policy last, and trying various other tactics I was unable to change this behaviour.
To apply this setting, you can also use the following key location:
When set here, the value of 2701 will not revert back to 3 (disabled), and HTML5 video playback will be enabled.
You can set this via GPP as below.