I understand that the menu is gone in vimeo when you use it and need to restart Firefox to get it back. I am unable to reproduce this, however please make sure that other extensions or add ons are not interfering with the built in Vimeo player.

You may need to update your operating system to support full screen apps and menus via https://discussions.apple.com/thread/3204344?start=15&tstart=0 and http://support.apple.com/kb/DL1459

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You can reload web page(s) and bypass the cache to refresh possibly outdated or corrupted files.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 remove cookies only from websites that cause problems.

"Clear the Cache":

• Firefox > Preferences > Advanced > Network > Cached Web Content: "Clear Now"

"Remove Cookies" from sites causing problems:

• Firefox > Preferences > 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

It happens when I go out from full screen for Vimeo. Attached images are showing how it looks like and how it should look like.

You can try to disable OMTC and leave hardware acceleration in Firefox enabled.

• about:config page: layers.offmainthreadcomposition.enabled = false

You can open the about:config page via the location/address bar. You can accept the warning and click "I'll be careful" to continue.

• http://kb.mozillazine.org/about:config

You can try to disable hardware acceleration in Firefox.

• Tools > Options > Advanced > General > Browsing: "Use hardware acceleration when available"

You need to close and restart Firefox after toggling this setting.

• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themesYou can check if there is an update for your graphics display driver and check for hardware acceleration related issues.
• https://support.mozilla.org/kb/how-do-i-upgrade-my-graphics-drivers

Thanks for the suggestions! I have tried them all but the problem still exist.