The feed contains iframes (youtube embeds) as part of the content of many posts.
These used to show up and still do on old entries, but since maybe a month back they no longer appear in Newsblur despite still being in the feed.
Look at entries title Inside Star Citizen as an example.
Are they intentionally being stripped out?
I have the same problem with a feed not showing, for instance this frame excerpted from a direct curl of the feed:
<iframe style="border: none" src="//html5-player.libsyn.com/embed/episode/id/19371707/height/360/theme/legacy/thumbnail/yes/direction/backward/" height="360" width="100%" scrolling="no" allowfullscreen webkitallowfullscreen mozallowfullscreen oallowfullscreen msallowfullscreen></iframe>
(This happens also on the beta site.)
Thanks for bringing this up, I found the bug and fixed it. It should also work retroactively, so videos should show up in older stories.