VLC media player is one of the best open-source cross-platform video player out there. I play my videos through WiFi from a LAN Buffalo NAS Storage(LinkStation Pro) without any problems for six months.
It can play most of the media filetype out there (.mkv, .flv, .avi, .mp4, you name it), check here for full list. It is a cross-platform media player, with versions for Microsoft Windows, Mac OS X, Linux, BeOS, MorphOS, BSD, Solaris, iOS, and eComStation. All the must have function are included on the player, so no worry to miss out any great features while switching from other player.
According to 9to5mac.com, the VLC 2.0 “…includes enhancements such as a native full screen mode in Lion, a redesigned subtitle manager, support for multiple video files inside RAR archives and enhanced video output modes. The Mac version will also support Blu-ray media, and Windows users will get to enjoy a 64-bit version.” You can read the full changes on the changelog.
i) Just download .exe for windows or .dmg for Mac
ii) Install and done
9To5Mac: VLC 2.0 arriving with all-new UI, native full screen in Lion, Blu-ray support, more