That assumption may indeed be false.<p>See here[0] in the FAQ &quot;What does this mean for downstream users of the Firefox code base?&quot;<p><i>&gt;&gt;&gt; The solution consists of three parts: the browser, the CDM host and the CDM.<p>&gt;&gt;&gt; However, the CDM will refuse to work if it finds itself in a host that isn’t identical to the Mozilla-shipped CDM host executable.</i><p>At first, I interpreted this to mean Mozilla, not Adobe, had implemented the restriction due to some particulars about the deal with Adobe.  But I was wrong...<p><i>&gt;&gt;&gt; This leaves downstream users of the Firefox code base with the following options:<p>&gt;&gt;&gt; 4.  Making arrangements directly with Adobe to get a non-Mozilla CDM host executable recognized by the CDM.</i><p>In other words, the CDM can discriminate on the CDM host.<p>My only hope is that this is non-standard temporary behaviour while Mozilla finishes EME.  Otherwise, this is extremely terrible.<p>[0] <a href="https:&#x2F;&#x2F;hacks.mozilla.org&#x2F;2014&#x2F;05&#x2F;reconciling-mozillas-mission-and-w3c-eme&#x2F;" rel="nofollow">https:&#x2F;&#x2F;hacks.mozilla.org&#x2F;2014&#x2F;05&#x2F;reconciling-mozillas-missi...</a>