2.1.100 [W3C-HTML51] Section 6.7.6 Page load processing model for media
V0256: Audio and video media are not loaded into a Document; instead a download is attempted
The specification states:
... Page load processing model for media When an image, video, or audio resource is to be loaded in a browsing context, the user agent should create a Document object, mark it as being an HTML document, set its content type to the ... MIME type of the resource (type in the navigate algorithm), ... append an html element to the Document, append a head element and a body element to the html element, append an element host element for the media, as described below, to the body element, and set the appropriate attribute of the element host element, as described below, to the address of the image, video, or audio resource.
Audio and video media are not loaded into a
Document; instead a download is attempted.