YouTube is a video-sharing website created by three former PayPal employees in 2005. Now under Google's  acquisition, YouTube is the most viewed video sharing website on the  internet. As a result, almost 24 hours of video content is uploaded to  this site per minute. With so much video content being uploaded, people have  felt the need to download videos but YouTube does not allow users to  download videos. So what does a user  do?
Well nothing, s/he just reads this article and learn the many ways he can use to download Youtube Videos.
YouTube's Video Format: YouTube uses the FLV( Adobe Flash Video)  format to display the various types of videos. The reason for this is  that FLV files use comparatively less amount of storage space for the  same quality of the video.
How to Play YouTube Videos: To play FLV media in browsers,  you need to have Adobe's Flash Player plugin installed. To play FLV  format in your PC, you need to have a Media Player capable of playing  FLV videos. VLC Media player is one such free media player which can  easily play FLV files.(To download VLC Media Player and other essential  software, visit 
5 Essential free software for Windows PC.)
Download Youtube Videos via Internet Explorer: This technique  uses copying YouTube videos from 
Internet Explorer's Temporary Files  Cache. A temporary files cache is a collection of items which are  stored on the disk to load them quickly from the disk without  downloading them again. Not only Internet Explorer, but almost all  browsers have a temporary files cache. But most of these browsers store  the files in cache without any extensions leading to complexity in finding saved videos. On the other hand, Internet Explorer stores the file "as it is" in its cache. To download YouTube/FLV Videos via Internet  Explorer, follow the instructions given below:-
For Internet Explorer 6 and earlier versions:-
- Play the video of your choice in Internet Explorer.
- Go to Control Panel. Click on switch to classic view in the sidebar.
- Click on Folder Options.
- Click on View Tab and encircle Show hidden files and folders.
- Go to My Computer.
- Click on your System Drive.(The drive containing your Windows files.)
- Click on Documents and Settings.
- Click on your User name.
- Click on Local Settings.
- Copy your Temporary Internet Files folder and paste it to your desktop.
- Search the pasted folder for "*.flv" without the quotes. And play  the files to find your video. Copy your found video and paste it to the  location of your choice.
For Internet Explorer 7 ,8 and 9:-
- Play the video of your choice in Internet Explorer.
- Go to Control Panel. Click on switch to classic view in the sidebar. 
- Click on Folder Options.
- Click on View Tab and encircle Show hidden files and folders and de-select Hide protected Operating System Files.
- Windows XP Users, follow the instructions given above for IE6 after Step 4.
- Windows 7 and Windows Vista users, navigate to your system drive.
- Navigate to Usersname\AppData\Local\Microsoft\Windows\.
- Copy the Temporary Internet Files folder and paste it to your desktop.
- Search the pasted folder for "*.flv" without the quotes. And play  the  files to find your video. Copy your found video and paste it to the   location of your choice.
Downloading YouTube Videos via third party software: Due to the  popularity of YouTube, many third party companies have manufactured many 
 software programs to download YouTube videos. A simple web search  containing "free software to download Youtube videos" is likely to  return a lot of such software programs.
Downloading YouTube videos via Real Media Player: 
Real Media Player states that it is the best free media player available  to play, manage and  download all your mp3, flash and video files. I do  not quite agree but still, Real Media Player offers a very good plugin  with which you can download YouTube videos easily. Whenever Real Media  Player detects a flash video, it offers an option to download the video  right on top of it.
Downloading YouTube Videos in Mobiles: Mobile Users can use 
Bolt Browser  to download YouTube videos directly to their mobiles. Bolt  automatically re-formats the video into a version supported by the mobile which can then be easily viewed. 
Opera Mini  can also be used to download YouTube Videos directly but Opera has some  bugs when it comes to reformatting videos according to specific  mobiles.
Downloading YouTube Videos Directly without the use of any Software in Mobiles and Computer:
Update:3outube.com is facing technical difficulties and is not available temporarily. SaveYoutube is a service that works similarly. To use it, just change the URL of a video from "http://youtube.com/your-video" to "http://
saveyoutube.com/your-video".
This is the easiest method to download YouTube videos with no brains  involved. All you need to do is copy the URL of your YouTube Video.(e.g.  http://youtube.com/your-video) Replace the y of YouTube to 3 so that  your URL becomes http://3outube.com/your-video. Then press Enter.  Click on the the format in which you wish to download and your download  will start automatically. (
Note: 3outube.com is not Youtube.com. It is a third party site that gives links to download YouTube videos. )
|  | 
| Charlie bit my finger. Most popular Youtube Video | 
Third Party Websites to Download YouTube videos: There are many  free third party websites on the internet which offer you to download  YouTube videos just by entering the URL of the video, selecting the  format and clicking on the download button. Few such sites are:-
1.  
MP4youtube:  You can download videos in MP4 format, 3GP format and FLV format in the  quality of your choice using this online video downloader.
2.  
Vixy: Vixy offers you  to download youtube videos in .MP4 format, AVI format, .MOV for  Macintosh, .3GP format for mobiles and .MP3 format for Audio Players.
3.  
Keepvid: Keepvid  allows you to download youtube videos in a wide variety of formats  including .MP4, .3GP( high and low quality) and yeah, .FLV format.
 4.  
SaveVid: SaveVid  also offers downloading YouTube videos in various formats with the option of downloading them in different qualities.
So,  that brings us to the end of this article. If you know some other  ways to download YouTube videos, feel free to send me an email and they will be included in this article.
Note: Downloading Videos is against Youtube's policies.