YouTube is the first and the fastest free video depot for netizens. Various videos of interest are being uploaded and viewed by most net users around the globe. You might be asking “How can I save YouTube videos into my hard disk?” multiple times, then lots of third-party softwares and sites emerge having the same goal–to download the video from YouTube given the video URL into your hard drive. Sweet.
But do you know the fact that when you actually watched a YouTube video, it is already saved in your hard drive? Yes, it is in your browser’s cache. I will give you a hint on how to find the video yourself, save it on another folder and watch it fullscreen with a video player.
In this tutorial, I will assume that you are using Windows XP Pro and Mozilla Firefox 2 as your platform and browser used to watch the videos.
First, go to the YouTube then search for a video. Watch that video completely or wait until the red bar goes full. That’s it! The video is saved in your browser’s cache. So, where can we find the browser cache?
Before searching, you have to know that YouTube videos are in FLV format. FLV stands for Flash Video.
Let’s begin the search. Go to “My Computer” then “Local Disk (C:)” and then go to the “Documents and Settings” folder. Select the folder of the profile you are currently using–usually the owner’s nick.
C:\Documents and Settings\[profile]
The next folder you have go into is somewhat hidden. On your current folder menu, click “Tools” then “Folder Options”. Click the “View” tab, enable “Show hidden files and folders” then click on the “Apply” button and “Ok”.
Now that you can see the hidden folders, select “Local Settings” then “Application Data” then “Mozilla” and then “Firefox” and “Profiles”. Then select the random folder that has “.default” after it and you should see the “Cache” folder, finally.
C:\Documents and Settings\[profile]\Local Settings\
Application Data\Mozilla\Firefox\Profiles\[random].default\Cache
You should see random files named with 11-characters. Those are files are parts of any web page you viewed. Now, how do we know if a file is an FLV video? Oftenly, videos are bigger than any web files. In that case you should pinpoint the biggest files. This is easily done by changing the folder view into detail mode. In the folder menu, select “View” and click on “Details”. Your folder view should become a list with details. Click on the “Size” tab twice to sort the files by size in descending order.
You should be seeing the FLV candidates. You might ask, “How can I be sure that the file is an FLV?”. When you open a file using text editor like Wordpad (though I recommend using a Hex editor), you should read the first three characters as “FLV”. If this is the case, then the file is a Flash Video. Close and do not save the file you opened, instead, open it with a video player capable of reading FLV files like VLC media player. After you searched the FLV files you are looking for, save them in a separate folder and rename it with any name you choose then append an .FLV extension.
In case, you are using Internet Explorer as your browser, you have to search for the cache folder by yourself. Sorry, but I am not using IE anymore so I can’t tell you the exact cache folder.
Enjoy watching your videos!

Firefox have CacheViewer extension:
https://addons.mozilla.org/firefox/2489/
I didn’t know about the “about:cache” earlier. The CacheViewer extension is a must to install! Thanks for the info.
Hi Jon ! nice article you have there!
I use http://www.savetube.com to save youtube videos.