how to download youtube video ?

Steps-1 Download and install ClipGrab from ClipGrab website. ClipGrab is a free and open source program available for Mac, Windows and Linux.

Steps-2 Copy the URL of the YouTube video you would like to download.

Steps-3 Paste the URL into the ClipGrab window.

steps-4 Select the format and quality you want to use. (e.g. MPEG4 and HD 1080p).

steps-5 Click on the "Grab this Clip!" button to start the download.
use URL copy-paste procedure to other some websites.
How to download youtube videos without software?

steps-1 Open youtube website and select a video that you want to download. Select the web page address of the youtube video and copy it. To copy it’s very easy, just block the address link, press right mouse button and select ‘copy’.
Step 2. Open website ‘Download Youtube Videos’ Open another tab of your browser and type ‘http://downloadyoutubevideo.org”.
Step 3. Paste the youtube video link After ‘download youtube videos‘ web page is opened, go to ‘youtube URL:‘ text box, paste the youtube link and then click ‘download‘ button.
Step 4. Download the file

If the process succeed, you will get ‘Download video link‘ followed by video file name. Put your mouse pointer on it, press right mouse button and select ‘Save Link As‘ menu. If there is no problem with the download process, you will get a filename with ‘flv’ extension.