With the following HTML: <a href="http://www.flickr.com/photos/44399775@N06/7262483786/"><img src="http://farm8.staticflickr.com/7214/7262483786_c55c5c7bd1_n.jpg" alt="guild wars 2 beta delay" width="320" height="180"></a>
Is there a setting somewhere that controls this width? Was it a change with oEmbed? I noticed that 500 and 320 are both options in the “Share” drop-down on a Flickr page. Is there a reason the embeds are grabbing the “Small” version instead of the “Medium?”
There have been longstanding issues with the Flickr oEmbed endpoint only returning images of a specific width. For example, I just tested the first embed link on 3.4.2 and 3.5 test builds, both times it wouldn’t embed anything wider than 320px. You might try inserting the images from the URL if you have the size on Flickr you want.