Can you post a link to a publicly accessible page (i.e. no authentication or signing on required)?

Firefox 42+ has a Tracking Protection feature that is enabled by default in Private Browsing mode. When you are in private browsing mode then Firefox can show a shield icon at the left end of the location/address bar that some content is affected.

You can disable this feature in "Options/Preferences > Privacy" or via the about:privatebrowsing page that get when you open a New Private Window.

• Options/Preferences > Privacy: "Use Tracking Protection in Private Windows"

• https://support.mozilla.org/kb/tracking-protection-firefox
• https://support.mozilla.org/kb/control-center-site-privacy-and-security-firefox

If you use extensions (3-bar Menu button/Tools > Add-ons > Extensions) that can interfere with loading content (e.g. Adblock Plus, NoScript, Flash Block, Ghostery) then make sure that such extensions do not interfere with loading content. There is security software that can interfere with loading content, so check that as well.

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

Hi Cor-el,

Thank you so much for your reply :)

After disabling "Use Tracking Protection in Private Windows", embedded Youtube video started working once, then stopped showing up again.

Then I disabled "youtube.com/embed/*" in custom filter of Adblock Plus. I dont remember whether I blocked the embedded youtube videos myself. Now all embedded youtube videos are working.

I also enabled "Use Tracking Protection in Private Windows" again.

Thanks again :-) Jay