Wow @ the mobile version. How many posts typically fit on a screen these days?
I took a quick look at my news feed, and found that non-sponsored "full screen" posts are very common. A few recent examples:
Obviously, it's very popular to share photos and videos on Facebook, and it's understandable that those forms of media will take up a large percentage of small mobile screens. Not really an issue specific to advertisements.
Mobile: http://i.imgur.com/kQlmh.png
Desktop: http://i.imgur.com/ZiOqX.png
This appeared in my news feed last night, and is still there now. It moves like a normal item (i.e., its not 'sitckied' to the top or anything like that).
On mobile its pretty jarring. Bigger than any other posts.