[whatwg] Video with MIME type application/octet-stream

[Boris Zbarsky]

>> Of course nothing prevents us from saying UAs MUST NOT sniff but if they do
>> anyway they MUST use a given algorithm, right?
>
> That's a contrary to duty imperative, which is something that's been
> puzzling philosophers for centuries.  A more sensible requirement
> would be that user agents SHOULD NOT sniff (for reasons XYZ), but, if
> they do, they MUST use a the following algorithm.

Except that in practice SHOULD NOT is treated as carte blanche to do the 
undesirable thing.  It has no teeth.  MUST NOT doesn't much either, but 
it's _something_ at least (in the sense that one can clearly claim that 
violating a MUST NOT is a bug).

-Boris