As the guys said - its' basically a blocker for ads and other 'nasties'. On a side note - for those that use IE or EDGE, Ghostery is a great extension/add-on. You can block ads, autostart videos, cookies, tracking data etc etc. The best part is that it speeds up page loads no end... Give it a try!
It's definitely weird, thumbnails for uploads but full size for img coded from a third party site. I'm glad the third party linking is finally available, this was basically the only forum I've ever used with tags couldn't be used. I actually much rather 3rd party linking anyway, I just put everything everything onto imgur.com and then I can share the link anywhere.
