http://www.whatwg.org/specs/web-apps/current-work/multipage/video.html#mime-types
There was some discussion about this, last in <http://lists.whatwg.org/htdig.cgi/whatwg-whatwg.org/2010-May/026409.html>
I've tested Firefox 3.6.4, Firefox 4.0b1 and Chrome 5.0.375.99 and none return "maybe" for canPlayType("application/octet-stream"). I couldn't get meaningful results from Safari on Windows (requires restart to detect QuickTime, perhaps?).
It would appear that Opera is the only browser that supports application/octet-stream. At the time I added this, it was simply because it is true, maybe we can play it. However, I see no practical benefit of this spec-wise or implementation-wise. Since no other browsers have implemented it, I am going to remove it from Opera and hope that the spec will be changed to match this.
-- Philip Jägenstedt Core Developer Opera Software
