Sometimes embedded playing of youtube video seems forbidden…

To enable embedded player in OG topic proceed with following steps:
Login to YouTube.
Go to your Video Manager.
Go to the video you want to turn on embedding for and click Edit.
Under the video, click Advanced settings.
Under "Distribution Options,"check the Allow embedding checkbox.
Click Save changes.
Is it only possible to post own videos from our YouTube channels?
Can we embed other random videos from YouTube?
Sure, you can embed all publicly accessible youtube videos…
Could you direct me to the how-too? 
I’m currently doing searches to find it out 
Go to youtube, then use “Share” button and it will generate address (URL) for you.
Then just paste this URL on separate line in post editor here…