YouTube is a phenomenon unto itself and possibly the most successful product for Google after Google search. Launched back in November 2005, the website attracts more than 1 billion unique users every month, and more than 6 billion hours of video are watched during the same period.

Although it might be frowned upon, there are many legitimate reasons to download a YouTube video. One is when you've recorded a video, uploaded it to YouTube, and then lost the original copy. And then there are copyright-free works to consider — from open source and creative content videos to those available in the public domain. You might not even be interested in the video and may just want to download its audio (or soundtrack) instead.

As with peer-to-peer (P2P), just because a technology can be used illegally, that doesn't mean it should be banned. From the myriad of options available, we've plucked out what we consider to be the best ones. They're free, but it's worth bearing in mind that they they may try to install add-ons that you haven't asked for - such as search engine toolbars or software to clean your computer's registry - that you can opt out of.

With that out of the way, here are our top 5 best YouTube downloaders. If we've missed any, feel free to comment and let us know.

1. Freemake Video Downloader

Download Freemake Video Downloader

Freemake Video Downloader is a simple-to-use tool for downloading YouTube videos, along with their accompanying audio, in a few clicks. Simply paste in the URL of the video you want to download and click 'Paste URL' to set it running, or install the Firefox add-on to start the download from the YouTube page itself by right-clicking on the video.

Freemake Video Downloader

The program comes with a slew of extras, including the ability to download YouTube Playlists and convert videos into multiple formats - including AVI and MP3. One of the program's more useful features is a nifty restrict bandwidth option that allows you to slow down your downloads if your internet connection isn't the fastest in the world. This allows you to keep them running smooth as butter while carrying out other tasks - such as streaming online video or gaming.

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2. Free YouTube to MP3 Converter

Free YouTube to MP3 converter

YouTube is first and foremost a resource for watching videos, but there's nothing to stop you just ripping any video's accompanying audio. And, of course, there's more to YouTube audio than background music. Guitarists, pianists and other musicians, for example, could benefit by downloading one of the many instrumental backing tracks uploaded by professional and amateur musicians.

Free YouTube to MP3 converter

Looking for a funky guitar backing track in B-Minor to jam along to? Or how about downloading a karaoke track for that party you're hosting at the weekend? With Free YouTube to MP3 converter, you can do it in a snap. Copy the URL of the YouTube video you want to rip the audio from and open the program and hit CTRL + V to queue it up.

Before ripping, you can select the quality you want to rip the audio in from a variety of formats - including MP3, M4A, AAC, WAV and OGG. Next, pick your desired bit-rate quality and hit download to send it hurtling down the wires.

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3. aTube Catcher

aTube Catcher

With aTube Catcher you'll get the usual array of tools to download and convert YouTube videos (with audio), but it does a whole lot more too. One of its handier features is the ability to resize video, which allows you to cut out parts of clips for your own projects (if they're copyright free, of course) or lower the size of videos before saving them to your computer.

aTube catcher

Another cool feature not found in many other programs is the Stream Capture tool, which allows you to load up a video stream from YouTube or other video sites to save streamed content straight to your hard drive, meaning you don't have to wait until a program is made available to officially download, which can take days - or even weeks.

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4. Free Studio

Download Free Studio

Where some YouTube video downloaders focus on performing a single task well, Free Studio offers a comprehensive conversion package that can do tons more after you've made the rip. It's simple enough to get going: load up the program and you're presented with the option to download a YouTube video, or rip its audio as an MP3.

Free Studio

From there, you can choose from multiple conversion options to optimise the file for a certain device. Choose the mobile option, for example, and with a single click you can convert the video for viewing on Android, BlackBerry, HTC, Motorola, Samsung and other handsets.

It means that factors like resolution, bit-rate quality and suitable audio codecs are automatically chosen and optimised, perfect for making sure you can view the video offline on your mobile device with no compatibility problems. There's also the ability to burn your video or audio track to a CD or DVD, and you can even give videos a psychedelic3D-type effect using the built-in 3D Video Maker.

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5. YTD

Download Free Studio

YTD is a no-frills video downloading tool that features the handy option of converting your files before they're ripped, saving you from having to do it afterwards. And unlike some other downloaders that only support YouTube, YTD is compatible with a whole range of video sites: from DailyMotion to Facebook and beyond.

YTD Video Downloader

It may not be the most feature-packed option on our list, but its uncluttered, compact UI makes it a suitable choice if you're something of a prolific video downloader, allowing you to instantly get a snapshot of how many downloads you've got on the go.

You're also provided with information on their progress, the speed that they're downloading and how long it'll be until they're nestled on a corner of your hard drive to be viewed whenever you're ready.