1) First of all, to make your job easier, you are advised to Get a toolbar for faster access to youtube.com.

2) Click your favourite video clip, you can see the URL in your browser becomes something like this

3) highlight the URL (like above) and right click the mouse and select "copy"

4) Paste the URL at our download page

5) When the download link shows, You should right-click -> "Save Target As" OR copy and paste the link into your download manager. Note: You must change the file extension to .flv

6) The .flv file is not a common multimedia file, you need a software called FLV player to play it

7) Install the FLV player into your computer

8) Select the video clip that you downloaded and play

9) If you want to convert the FLV video and play it in IPod, PSP, mobile phone(3GP format), then you need to download FLV Converter

Related help: youtube to ipad converter | rip dvd for ipad | dvd to ipad ripper