Thank you for contacting Fixya Support, I am glad to assist.
Depending on your web browser, you first should clear the Cache of the select web browser and then reset the browser.
I would also recommend you try this simple procedure I am providing you from MacOSX.com forum regarding the inability to launch or load Facebook:
Link: Cannot Load Facebook on my MacIn regards to video suggest you try, depending on the web browser you have (Safari or Firefox) is to check the Add-ons of that browser, for any updated plug-ins for viewing Youtube videos.
If you are accustomed to using just one browser, experiment with different browsers.
The most commonly used web browsers for Mac OS X are:
* Safari (Built-in web browser from Apple direct)
* Firefox (Developed by Mozilla)
* Camino (Developed by Mozilla)
* Opera (Developed by Opera Software)
For your current web browser, if you want to keep working on the video playback for your Youtube, you should clear the Cache of the web browser and reset your browser.
These are some general practices to resolving the stated issues you are having with launching Facebook and loading YouTube videos.
Let me know if this helps.
Regards,
-Mactechtrainer