I bet "how many people downloaded the DRM-less version" is an important statistic for Mozilla - Having FF in the middle of an automatic update, I'll be getting the other version however, and I wonder if having disabled this feature, will the browser call home to count towards it...

> I wonder if having disabled this feature, will the browser call home to count towards it...

It will not. Currently the only telemetry related to EME is the VIDEO_EME_PLAY_SUCCESS histogram, which counts successes/failures of playback. It's only enabled then EME itself is enabled, though.

Wait a second.

Doesn't EME imply a kernel component? To safeguard the encryption keys and to generally complicate an access to the raw media? If so, does it mean that this Firefox update touches the kernel?

It does not imply a kernel component. From the point of view of the browser, EME is an API to a sandboxed binary (the CDM) that decrypts video frames and sends them back to the browser, which then presents them to the user. The CDM might use kernel facilities for storing encryption keys.

Bad wording.

Does this update add Adobe's stuff into kernel or does it not (e.g. if Adobe is just piggy-backing on Windows PMP)? Can anyone from Mozilla comment on this?

This is a principal question, because if there is an Adobe's kernel DRM driver in this update, then it makes sense to go with the "EME-free" update instead of adding and then, hopefully, removing 3rd party junk from the kernel as per that Mozilla KB linked elsewhere in this thread.

I work at Mozilla on the EME team.

Neither Firefox nor the Adobe CDM install any kernel code. The Adobe CDM is, conceptually, the Flash Player's DRM code repackaged to work with Firefox's CDM API. And the Flash Player doesn't need to install new kernel drivers. Studios have different DRM requirements for video quality levels like HD, non-HD, "Studio HD", and "Ultra HD". For higher quality video, studios might require secure hardware path. Even this level, AFAIU, doesn't require new kernel drivers because Windows already has APIs for this.

Thank you.