Well, you have selected "Original size"...
I guess it should not be the default for embedding, though.

Yes, it's the default... which seems unwise for multi-megapixel images. :)

This is pretty rough on the unsuspecting user.

It's unclear to me why the HTML output is not directly equivalent to the wikitext --> HTML output (i.e., the HTML we provide to users via MediaViewer's embed feature should try to be identical to the HTML we provide to users already via "[[File:Foo.png]]"-type syntax). Currently the two HTML outputs are not directly equivalent.

(In reply to Tisza Gergő from comment #1)

Well, you have selected "Original size"...

If I go to https://en.wikipedia.org/wiki/State_of_the_Union#mediaviewer/File:Livingood_Obama_State_of_the_Union_2011.jpg, click "Use this file", click "Embed", click "HTML", and then select "small 217 x 145 px" from the drop-down menu, the suggested embed HTML is:

<p><a href="https://commons.wikimedia.org/wiki/File:Livingood_Obama_State_of_the_Union_2011.jpg#mediaviewer/File:Livingood_Obama_State_of_the_Union_2011.jpg"><img src="https://upload.wikimedia.org/wikipedia/commons/6/65/Livingood_Obama_State_of_the_Union_2011.jpg" alt="Livingood Obama State of the Union 2011.jpg" height="145" width="217"></a><br>"<a href="https://commons.wikimedia.org/wiki/File:Livingood_Obama_State_of_the_Union_2011.jpg#mediaviewer/File:Livingood_Obama_State_of_the_Union_2011.jpg">Livingood Obama State of the Union 2011</a>" by <a href="//commons.wikimedia.org/wiki/Pete_Souza" title="Pete Souza" class="mw-redirect">Pete Souza</a> (<a href="//en.wikipedia.org/wiki/Executive_Office_of_the_President_of_the_United_States" class="extiw" title="w:Executive Office of the President of the United States">Executive Office of the President of the United States</a>) - <a rel="nofollow" class="external free" href="http://www.whitehouse.gov/photos-and-video/photogallery/2011-state-union-address">http://www.whitehouse.gov/photos-and-video/photogallery/2011-state-union-address</a>. Licensed under Public domain via <a href="//commons.wikimedia.org/wiki/">Wikimedia Commons</a>.</p>

<img src="https://upload.wikimedia.org/wikipedia/commons/6/65/Livingood_Obama_State_of_the_Union_2011.jpg" alt="Livingood Obama State of the Union 2011.jpg" height="145" width="217"> is pretty clearly wrong. You're embedding the full-size image and resizing it in-browser. This is a major bug.

Created attachment 16492
Screenshot of https://en.wikipedia.org/wiki/State_of_the_Union#mediaviewer/File:Livingood_Obama_State_of_the_Union_2011.jpg, 2014-09-16

Attached:

(In reply to MZMcBride from comment #5)

Created attachment 16492 [details]
Screenshot of
https://en.wikipedia.org/wiki/State_of_the_Union#mediaviewer/File:Livingood_Obama_State_of_the_Union_2011.jpg, 2014-09-16

I'm well aware that the drop-down menu says "Original file <span garbage>", but it's clearly having issues (I'll file further bug reports) and the HTML markup makes it clear that the small option has been selected by the user.

Attached:

Currently we fetch thumbnail URLs when the user first selects the given file/size combination, which comes with a lot of quirks (such as the embed text appearing seconds later than the menu select action). For a decent fix, we would want multi-size support in imageinfo.

In T69323#839673, @Tgr wrote:

Lowering priority as we do not plan to work on this anytime soon.

Assuming the behavior is still the same, as I said in T69323#736333, I think this is a major bug. Large images aren't, like, uncommon and we're telling users to embed really big images to then have their browsers resize them locally. Owww.

Mass-removing the Multimedia tag from MediaViewer tasks, as this is now being worked on by the Reading department, not Editing's Multimedia team.

Still a bug that probably should be fixed.