Since the update to Flash Player 11.3, a protected mode was added as a new security feature for Firefox 4.0 and above on Windows Vista and higher. This security enhancement is designed to limit the impact of attacks from malicious Flash content.
When Flash content won't display: errors on YouTube like "An error has occurred Please try again later." or when the Flash Player freezes randomly.
First solution, if RealPlayer is not installed
- Go https://get.adobe.com/flashplayer/?loc=fr
- Uncheck the McAfee installation,
- Click Download Now,
- Click Save the file,
- Then at the end of the download, run Flash Player
- Install it (This will update Flash palyer)
- Restart Mozilla Firefox.
Second solution, if you have RealPlayer
- Please disable the Real-Player downloader plug-in.
- Launch RealPlayer
- Click on the RealPlayer icon in the upper left corner and select Preferences
- Select Download and Recording.
- Uncheck "Enable Web downloading and recording for these installed browsers"
- Click OK and close RealPlayer,
- Restart Firefox.