MakeInstantPlayer gets around this problem by avoiding the need to even have the right player installed because it creates an EXE file that can be opened by anyone and played anywhere. There's no need to install any codecs or any player with MakeInstantPlayer.
MakeInstantPlayer uses the MPlayer compressor so that conversions are quite quick but the quality remains very good. However, the MakeInstantPlayer EXE files aren't exactly small so you'll need to either ZIP them up or transfer them by some other method than e-mail to friends. There is a certain amount of customisation you can perform too in MakeInstantPlayer - you can also add a URL with an image to appear before it plays and also select whether you want it to open in full screen mode or shrink mode when it's opened.
MakeInstantPlayer is a great way to send files to friends that either don't have the right player installed or not the right codecs.