To watch Weeds online you will first need to install the Divx webplayer onto your computer.
Once you have installed the DivX webplayer onto your computer go to http://www.ninjavideo.net and click the top link under "Ninja Video Helper" to launch the helper Beta. Once you do that, click television shows, then go down the column to the right and click Weeds. Pick what season and then episode of Weeds you want to watch then follow the prompts online to fill in the letters corresponding to the code to watch the Weeds episode. Its very easy. I will add links in the resource section to get you right to watch Weeds on Ninja Video.
An alternative to going to http://www.ninjavideo.net would be going to http://www.surfthechannel.com and then click on Channels bar, followed by clicking on Television. Once there, you can find Weeds seasons 1-5 by clicking on W in the alphabet, then Weeds. Click what season and episode you want to watch, and then click the Weeds megavideo links or Weeds Tudou/Youkou links (though they buffer a little slower). I will add links in the resource section to allow you to get right to watch Weeds on Surfthechannel.