I need a audio and videoplayer that is usable both in non flash-browsers (such as iphone-safari) and in non html5-video-enabled browser (such as all old browsers)
Apart from this clean asthetics(think vimeo), support for many codec-types and easyness to implement are all bonuses.
Free or paid doesn't matter!
I can't think of any player I have seen for HTML5 that plays both video and audio files (like mp3's), but JW Player - one of the most popular Flash based video players out there - now support HTML5 video. And it supports audio files when Flash is available:
http://www.longtailvideo.com/players/jw-flv-player/
VideoJS seems good, but I don't know about audio support, it's a video player that falls back on Flash when HTML5 is not supported: http://videojs.com
I haven't found a way of playing audio and video through a webpage on iPhone without using the fullscreen QuickTime player. Even when trying to trigger a sound in JavaScript