MPlayerX is the latest app to leave due to the sandboxing restrictions:
> MPlayerX will lose so many features if it adopted Sandboxing, it could not load the subtitle automatically, it could not play the next episode for you automatically, it could not save the snapshots to the place where you want to, etc. Without those features, MPlayerX were just another lame Quicktime X, which I could not accept.
I initially took a wait and see approach about the sandboxing restrictions, but I am having a hard time not taking a wholly negative view of them the more time goes on.
(via [Michael Tsai](http://mjtsai.com/blog/2012/08/18/mplayerx-leaving-the-mac-app-store/))