The DivX Plus Web Player allows you to play DivX videos from your web browser.
Install the program and it equips your PC with browser add-ons that mean you'll be able to use the DivX player with sites like YouTube, often delivering better performance.
The Web Player also plays many common video formats, including DivX, AVI, MKV, MP4 and MOV, as well as providing HTML5 <video> tag support. (You'll need IE8, Firefox 3.5+ Chrome 5+ or Safari+ for full support: IE7, Firefox 3.0 and Safari 4 can't handle HiQ or HTML5.)
And whatever you're playing, support for DirectX hardware acceleration may help to improve performance by offloading video rendering tasks to your graphics card (if it's up to the task).
That's the theory, anyway: the player is still a beta, however, and we had problems getting it to work exactly as it should. If you also run into difficulties, check the DivX Labs support forums for more advice.