I can't believe it's impossible to run MKV on QuickTime X. Anyone has an idea?
The MKV file container is not natively supported by QT. Having Perian installed allows QT to recognize/read the file container and determine what types of data are contained within the file. If the content is QT X compatible, it can then be played. In cases where the content is not supported by your system's codec component configuration, the file will not play. In still other cases, the data may not be playable in QT X but is supported by your system's codec component configuration and is playable by the QT 7 player. This would seem to be the case with the current file. In such cases where AVI or MKV files can be played by the QT 7 player, the QT X player may ask the user if he or she whould like to open the file in the QT 7 player if installed. However, since you do not have/want QT v7.6.6 installed, QT X is suggesting that you install it so the file can be played in that app.
It's really interesting to see that the video runs really fine on quicklook on Finder.
QuickLook is a different technology—it does not actually open the video file or "play" the actual encoded data. (As far as I'm concerned, it's magic.)
Why, for God sakes, it doesn't play on QuickTime X and keeps asking me to download QuickTime 7?
QT X is based on/targets the playback of new video technologies and techniques currently under development/developing over the next decade while QT 7 is the result of 20 years of development which, unfortunately, focuses on "legacy" technologies and techniques which are rapidly falling by the wayside. (I.e., as QT X becomes more and more modernized, it loses more and more of its "lagacy" capabilities.)
I've seen some people with the same issue - some of them got out of here without an answer, some said that installing Niceplayer and removing it later will make QuickTime X automagically plays MKV videos. But none of this worked for me.
You basically have two options here:
1) Convert the file to compression formats and/or file types that are QT X playback compatible or
2) Install a media player the can play you MKV file as it currently is.
Basically, no single player supports the playback/conversion of every possible media format/file type. I personally keep QT X, QT 7 Pro, VLC, MPEG Streamclip, and HandBrake installed for playback and/or conversion of various files. (E.g., I prefer VLC for the playback of BD AVCHD/DTS content and HandBrake for conversion while BD WVC1/DTS is not supported by either VLC or HandBrake but can be converted by QT 7 Pro or MPEG Streamclip with the Flip4Mac codecs installed but is not actually "playable"—skips too many frames—by these apps.) Thus, you need to configure your system/work flows to specifically support those files/file types you actually use on a day-to-day basis even if this means having multiple players/converters installed.
Thank you the answer. It covered up all my doubts about the topic and even about the technologies behind QuickTime X and QuickTime 7. Unfortunately I'll have to install many players to be able to playback all my media - which was something I was trying to avoid.
Anyway, you answer was of enormous help. Thank you.