YouTube Won't Play in Mozilla Firefox
YouTube may be a popular website for watching videos online, but it is not self contained. It requires you to have the proper software on your system before its videos will play properly. If your attempts to play videos from YouTube on the Mozilla Firefox browser are unsuccessful, you are probably missing the Adobe Flasher Player program.
All videos that computers play, be they online streams or read from a physical disk, are specially formatted data. Each data format has an associated program that reads the data, then converts it to the images and sound that you see and hear on your computer. YouTube, as well as many other video sites on the Internet, use Adobe's Flash program to broadcast videos. Consequently, if Adobe's Flash Player is not properly installed on your system, then you will not be able to view YouTube videos in Mozilla's Firefox browser.
Check Firefox Plugin
If YouTube won't play in Mozilla Firefox, then you can check to see if Flash is properly installed on your system. Type "about:plugins" into the browser's address bar to view a list of all the software plug-ins that are currently working with Mozilla Firefox. If Flash is properly installed, you will see an entry for "Shockwave Flash" on the page that opens. If this entry is not present, then Flash is not installed and you need to install it before you can watch YouTube videos in Firefox.
If you are running Windows or Apple's OS X, then the installation process for Adobe's Flash Player is straightforward and self-automating. You only need to navigate to the download page for Adobe Flash, select your operating system from the drop-down menu, and then select the latest version of the Flash player from the drop-down menu below it. If you are a Windows user, you need to make sure to select the Flash version for "Other Web browsers." After clicking the "Download" button, run the package that downloads for the automated installation process to install Adobe Flash. You need to close down Firefox during this installation process.
Many distributions of Linux have specific processes for installing Adobe Flash through their own respective package management systems. In addition to these processes, you can also go to Adobe's download page, select either the 32 or 64-bit version of Flash -- depending on the operating system -- then select the ".tar.gz" version to install. You can then decompress the downloading package with the terminal command "tar -xvf (downloaded-package-name).tar.gz," and then copy the "libflashplayer.so" file within the newly created directory to the "plugins" folder of the Firefox application directory. You need to restart Firefox after completing this task for the browser to load the Flash plug-in necessary to view YouTube videos.
Outdated Version of Firefox
Usually, Firefox automatically downloads and installs updates as they become available from Mozilla. These updates can solve any issues -- such as compatibility with the YouTube website -- the browser has displaying YouTube videos. If your version of Firefox is too old, it may not be able to play YouTube videos.You can manually update the browser by opening the About window. Open the "Help" menu, and them select "About Firefox" to update the browser.