YouTube playback errors can occur for multiple reasons, I've encountered errors when playing YouTube videos as well. Issues are known to be occuring when adobe flash is not up-to-date, go to the Adobe Flash Website to download the latest version.

Also, hardware acceleration is known to cause problems on some systems: To disable hardware acceleration right click a video, go to settings and uncheck the checkbox which states Enable hardware acceleration.

After this, try to play the video again.

You can try these steps in case of issues with web pages:

You can reload web page(s) and bypass the cache to refresh possibly outdated or corrupted files.

• Hold down the Shift key and left-click the Reload button
• Press "Ctrl + F5" or press "Ctrl + Shift + R" (Windows,Linux)
• Press "Command + Shift + R" (Mac)

Clear the cache and cookies only from websites that cause problems.

"Clear the Cache":

• Firefox/Tools > Options > Advanced > Network > Cached Web Content: "Clear Now"

"Remove Cookies" from sites causing problems:

• Firefox/Tools > Options > Privacy > "Use custom settings for history" > Cookies: "Show Cookies"

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

If you live in India then you can look at these pages:

World Cup 2014: 219 websites blocked in India, after Sony complaint - MediaNama:

• http://www.medianama.com/2014/07/223-world-cup-2014-472-websites-including-google-docs-blocked-in-india-following-sony-complaint/
• http://www.nextbigwhat.com/delhi-high-court-orders-block-google-docs-several-websites-297/
• http://delhihighcourt.nic.in/dhcqrydisp_o.asp?pn=119642&yr=2014