For reference, this is doing 1080p typical downloaded mkv files.
I never had a single problem with mplayer. It plays everything, no gui and using the keyboard to navigate is awesomeness and simplicity with no end, and I don't think I could ask for more.
But in those rare cases I do, like stylised subtitles or remembering where I stopped (which is no doubt configurable with vanilla mplayer, too), I use smplayer. Pity it's qt crap (one of the few good qt applications I use), otherwise the world would be perfect.
Yes it would. (be a problem with mencoder). They are the integrators of the software not me. I am the user. I use mplayer/mencoder, not ffmpeg. They use ffmpeg, wrap it with some eye candy and ship it as mplayer. If they decide to use mmfpeg tomorrow instead i would still be using mplayer and probably not notice a heck.
If all ffmpeg was doing was saying "hello world" instead of playing movies, mplayer team would notice and act. If it has subtle bugs instead, then suddenly the responsibility shifts to the user. As if they were the more skilled in newest trends in image processing etc.
The most stable player for me has been xine with xine-ui. Mplayer was good too, but needed dvd navigation (menus etc). I don't know if this has been implemented properly in the 1.0rc's, but in the past it had issues for me.
XBMC was good too. I really liked it, however again, dvd navigation I had issues with. I have some dvd's that won't play if dvd nav is disabled and others that won't play if dvd nav is enabled. I thought at first it might have something to do with distro's ie version/implementation of xbmc, but I have two different machines with two different distro's (kubuntu and Gentoo) with both having the same issues.
What I'd REALLY like (being a KDE user) is a plasmoid to replace xine-ui with all xine-ui's functionality, and have the video window appear only when a stream is playing/paused... and fullscreen of course.