Unfortunately for CoreAVC-for-Linux, a decent open-source project aimed at making more types of video and audio playable in Linux, Google has opted to take down the site they hosted for it following a DMCA complaint – even though it doesn't actually contain any code that the proprietary CoreAVC codec uses.
It's likely that the company behind the codec, CoreCodec, is the one who filed the complaint. However, neither they nor Google have stated as such. Media suites in Linux often depend on people who work to make 3rd-party and closed-source protocols and codecs function with free software. This often causes developers or companies behind those pieces of software to get upset, as they'd much rather make you pay through the nose for using their work. With most projects of this nature, it's likely they will simply find a new place to be hosted.