'application/octet-stream' is not a type the UA cannot render.
Test Result Test Assertion
FAIL Test passes if the text 'PASS' appears to the left and the text 'Your browser does not support media elements.' does not appear anywhere on this page.

http://www.w3.org/TR/html5/video.html#dom-navigator-canplaytype

The MIME type "application/octet-stream" with no parameters is never a 
type that the user agent knows it cannot render. 

[...]

The canPlayType(type) method must return the empty string if type is a 
type that the user agent knows it cannot render [...].