How to download video from YouTube

How to download video from YouTube without any software (use keepvid.com)?
Here is the instruction to download video from YouTube. without any software (use keepvid.com) :

1. Open video that you want to download from YouTube
2. Copy url address of this video



3. Open keepvid.com in new tab (I recommended you to use firefox or chrome)

4. Paste url address to keepvid download bar



5. If you first use keepvid, allow java script to run



6. Choose the size of video you want to download



7. Enjoy download :)
    download video from YouTube