YouTube is the biggest ever video portal or site which provides every and each kind of video you want.But there are many video which you want to watch again and again.But to do that  you have to go again on YouTube and reloaded the whole video again and if you are using slow internet connection than it takes hours to watch a video.We are  here posting the best way to download the YouTube video which are simple best and for free
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1.  Internet Download Manager (IDM)

Internet Download Manager (IDM) is a tool to increase download speeds by up to 5 times, resume and schedule downloads. But you can use this software for downloading any kind of online video.It download all flash video from all the site.Therefore i consider this tool the best of all as it do two work together.

Features:
Comprehensive error recovery and resume capability will restart broken or interrupted downloads due to lost connections network problems computer shutdowns, or unexpected power outages.
Simple graphic user interface makes IDM user friendly and easy to us
internet Download Manager supports proxy servers, ftp and http protocols, firewalls, redirects, cookies, authorization, MP3 audio and MPEG video content processing. IDM integrates seamlessly into Microsoft Internet Explorer, Netscape, MSN Explorer, AOL, Opera, Mozilla, Mozilla Firefox, Mozilla Firebird, Avant Browser, MyIE2, and all other popular browsers to automatically handle your downloads.
download idm free version here.

2.   Free YouTube Downloader

Free YouTube Downloader lets you easily download videos from YouTube and convert them to viewable video formats for your desktop, tablet, or other mobile device. It supports output to AVI, WMV, MOV, MP3, MP4, and many more formats. If you want the ability to save and view YouTube videos while offline, this is the tool to use.
Free YouTube Downloader is simple. Grab the URL of a YouTube video, paste it into Free YouTube Downloader, choose your output format and preferred video quality, then click Download. That's it. You can even save in high definition (720p or 1080p).
We would have liked to be able to name a file before downloading and saving it. But that's a minor inconvenience. Also, when installing, be sure to read carefully and uncheck items as needed. Otherwise you may find some unwanted installs, including a search toolbar and several partner shortcuts on your desktop.
Download the free youtube downloader

 

3.  Keepvid.

Keepvid can download all videos from YouTube easily. All you need to do is grab the Video Url and paste on the keepvid website , Click on the Download button and Choose the format and video resolution you want to download. Beside YouTube , keepvid can download videos from Dailymotion , Video , metacafe , mega video and Google video. It works on mobiles too , so you can Download any YouTube video in your mobiles too

Keepvid.com

4.  Zamzar

: Zamzar is a very useful website , that's why we have included Zamzar in our lists. Besides downloading YouTube videos , you can convert any YouTube videos to any format you want , you can choose 3gp if you want to play videos in your mobile ,  flv , wmv , mkv , avi for desktops ,convert for your i pad , i phone , i pod . So a variety of conversion options available for you. Zamzar works great and is highly recommended for you.

Zamzar.com
Here is the another

best way.

please watch the video below.