I found a funny link posted by my friend on facebook titled "Best Penalty ever!". The moment I click on the link to watch the video, it opened in a new tab instead of playing directly inside facebook. Moreover, it asked me to either 'share' it or 'like' it in order to unlock the video.
This is similar to a dark pattern called Friend Spam. There is no problem in the site developer to expect the user to share the video. The problem comes when the user is FORCED to share the video. It is the user's decision to make whether he chooses to share it or not. I would share the video only if I really like it, after watching.
On careful examination of the webpage using firebug, I found out that the lock is imposed by using an overlay '<div>' on top of the video. I wrote a bookmarklet to remove that overlay.
Drag the above link to your bookmars toolbar and click on it to unlock the video.