# strings -n 32 *.mkv
libebml v1.2.0 + libmatroska v1.1.0WA
mkvmerge v4.7.0 ('Just Like You Imagined') built on Apr 21 2011 01:13:14D
6FF85B7DCED32F007300C742D856715F
1A69EE1ADDA93FBD5D6D8438B795E8D0
1A69EE1ADDA93FBD5D6D8438B795E8D0
34C75898003E7200C198FBE1EE76C44F
678C08F13073C1040CBD74DFF0923808
F44B31C0ECD62FE58A6CF9D5F580BFC2
6E7E83749043DF9AA3DF6FF4374E2981

remove duplicate
apparently it's some blowfish...