http://dvcs.w3.org/hg/html-media/raw-file/tip/media-source/media-source.html#dom-endofstream

MSE maps endOfStream("network") to "If the connection is interrupted, causing the user agent to give up trying to fetch the resource" but HTML has no such section, it is called "If the connection is interrupted after some media data has been received, causing the user agent to give up trying to fetch the resource."

The "after some media data has been received" difference is relevant, because at least in Opera, this step of the algorithm can only be run when HTMLMediaElement.readyState > HAVE_NOTHING. Network errors reported when readyState is HAVE_NOTHING are treated as "If the media data cannot be fetched at all, due to network errors, causing the user agent to give up trying to fetch the resource".

For consistency with HTTP and other resources, I think the handling should be different "after some media data has been received", i.e. depending on readyState.