To start with MKV is not a format but a container. A bucket in which you can place videos of any encoding you can dream up into.
What I find is folk that want this to work but also do not want to know how it works or what a MKV is or what video encoding is.
They'll write they looked all over but the awful truth is that the explanation is technical and not one person or web site will convey the needed details to get a new to this person up to speed.
I have a problem getting my LS5700 smart TV to recognize and list the .mkv video files on my Windows 7 (64-bit) computer. I know the TV is capable of listing and playing these files, because I also have a USB hdd attached to the TV, and when I select this input ("10EAVS External") from the TV's "input list", It shows me all the files (AVI, MPG, VOB, MKV...) on the hdd and plays them without a problem. But when I select the input labeled "Win7 PC" from the TV's "input list", I get a listing of all the video files in the "My Videos" folder on the computer EXCEPT the MKV files. I am using a NetGear N900 router, and the TV is connected to the network through a wired LAN outlet, so I don't think bandwidth is a problem.
Can anyone shed any light on this? I have spent countless hours searching the net, and used the online CHAT to talk to an LG tech, but got nowhere.