Perhaps.  I preferred to think of it as 'direct', and
there was a technical point I was getting to.

JEditorPane is entirely suited to showing HTML
that is under the *direct control of the developer.*
This could apply to stuff coming off their own site
(presumably) or certainly to HTML that they specifically
supply with the app..

Another 'upside' to JEP in the situation the OP
outlined, is that the HTML does not even need to
be 'expanded' onto the local file system.

JEP can pull HTML (+ stylesheets and images etc.)
directly from Jar files.

[ OTOH - going the "rip off other people's sites" way -
- JEP is unsuited to that, the HTML quality is too unpredictable
- and trust..
 - untrusted applets cannot do it
 - an untrusted JWS app., *can* do it, but only with
the specific consent of the end-user. ]

Should I care?  I did not accuse them of either.
(A question is a question, perhaps an implication -
but not an accusation.)

To display HTML with pictures and text should be no problem in a
JEditorPane inside a JWindow or borderless JFrame.  Flash, video and
mpeg I don't think can be displayed in a JEditorPane.  You are probably
going to need to produce your own display pages.  MPEG if it is using
even a slightly new codec will require some third party software.  JMF,
which is no longer supported, will do some old formats.  There are some
new video and audio things coming with version 7 but that is a way off
and it won't be complete until version 8 I understand.

It would be really nice to have a JComponent that would display MPEG
video or Flash.

What on earth do you mean?  If there is no user,
what is the point of having GUI controls, let alone
HTML on-screen?

And what does the user get out of that?

If it is 'program help' you might look to JavaHelp*.

You seem to be being very secretive about the ultimate
point of this.  I think it is hampering the technical progress
of the thread.

* Note that it was only the second series of replies where
I (feel I) understand your use-case well enough to think of
'JavaHelp'.  Just how hard do you want to make it, for
people to help you achieve the goal (which is still unclear
to me)?