With Maxthon web browser, you dont need any 3rd party software to download youtube as it has been slipstreaming to the browser itself
Downloading youtube video made easy...
1. Open Maxthon browser and go to Youtube to view your favorite video
Maxthon will notify you that video URL is catched:

Click Options at the notify pop-up
2. You'll see direct URL to the video file here
Right-click to it and click Copy

3. Paste the video URL at the Address Bar in Maxthon browser

4. It will then notify you that the file is found and ready for download

5. Save the file as .flv

Note that you'll need to change the File Name and Save as Type as necessary
6. When download is finished, play it with your favorite FLV player

whalla.. =)