hey friend,
if you are willing to spend 8 euros you can buy a license for Twonky 7. Your MyBook Live is currently on version 5 and cannot play .mkv files.
WD would have to pay Twonky in order to give you the update and they don’t like spending money. It made me quite angry but in the end I spent the money and can now watch .mkv files without a problem.
You read how I did it on this post:
http://community.wdc.com/t5/My-Book-Live/My-Book-Live-3Tb-Samsung-40es5500-8Gb-HD-movies-Incorrect-file/m-p/450912
You can write me if you have questions
