You can also check this solution out:

http://www.videoconverterfactory.com/tips/youtube-an-error-occured.html

It provides the overall solution to YouTube error.

Some audio contained in YouTube video is copyrighted so that it cannot be heard.

What's more, YouTube uses the audio and video separation technology, and it may cause no sound on YouTube or audio and video are not synchronized. 

http://www.videoconverterfactory.com/tips/no-sound-on-youtube-online-playing.html

You can also find more information on the solutions in there