In particular Mike explains how a desktop video player and Flash Player differ. One obvious difference which surprisingly often gets overlooked, is that Flash Player is not just a video delivery medium but so much more than that. If you think back a few years there was barely any support for video in the Flash Player, and the only reason we hear so many complaints about its performance is due to the fact that so many people are using it these days. Flash has had an unprecedented growth curve when it comes to video delivery on the web, but it was a popular plugin way before then.
The issue Mike explains well in his article is that of users comparing apples to oranges a lot of the time: they compare a browser plugin to a desktop tool. In Mike's words, "a desktop player usually plays a linear media file from start to finish. Flash Player solves a different problem: It plays linear media files from start to finish while combining the video with a wide array of graphical and interactive elements (buttons, bitmaps, vector graphics, filters), as well as providing network, webcam, and microphone facilities, all programmable via a full-featured scripting language, and all easily accessible via a web browser using a plugin that most of the browsing population already has installed."

Mike's article in full can be found here. Please bookmark it and send to everyone who asks you next time: "Can you explain why a video player like VLC can play the same flv file with less CPU usage than the Flash Player?".

And the main takeaway: "The Flash Player works to solve the problem of making video accessible via the web browsing environment. In contrast, a desktop media player plays a file using a dedicated, single-purpose application."