User Agent: Mozilla/5.0 (Windows NT 6.1; rv:12.0) Gecko/20100101 Firefox/12.0 Build ID: 20120420145725 Actual results: Warning: HTTP "Content-Type" of "application/octet-stream" is not supported. Load of media resource [snip]foo.webm failed. Expected results: Hello, More than a bug this is a suggestion since i guess there is some reason not to support videos whose mime is not video/wemb... I think Firefox should be able to play videos with a content-type of application/octet-stream like other browsers do.. Thanks.

application/octet-stream is a general binary mime-type. The browser doesn't know what's inside of this file and would have to do content-sniffing but that is a violation of the http rfc. You should write bug reports for browser which are doing content-sniffing in this case. bug 589564 or bug 546129 are related

We're planning on implementing content sniffing in bug 567077.

Yeah, you're quite right. However, i think there are two conditions which can be met such that content-sniffing isn't needed and thus no http rfc is violated. 1) The url ends in .webm 2) It is only loaded through <video>'s src attributes. If both match, is Firefox still unable to play it? Obviously, not counting a possible corrupted video and/or faked filename ;)

@Chris Nice to hear these videos will be able to be played, whatever method is used ;-)