If the Facebook post "You cant watch this vide0 m0re than 20 seconds" is displayed on your wall or timeline, please report it to Facebook or delete it. This post is a scam that will trick you into installing a malware, or install malicious browser extensions. The browser extensions will redirect you to other scams.
There are different versions of this scam where the scammers change the texts, images and website addresses (URL).
Here are some copies of the scams:

- "You cant watch this vide0 m0re than 20 seconds. I bet y0u t0 watch this vide0."
- "95% 0f All People Cant even Watch This Video F0r More Than 20 Seconds. i dare you to get past the 25 seconds.Just click play"
- "99% 0f People Cant even Watch This Video F0r More Than 25 Secs"
If you click on this malicious post, you will be taken to a website that ends with .blogspot.com that will trick you into installing a malware by claiming that Divx plugin required.

Even if these malicious Facebook posts appeared as if they were posted by trusted friends, do not click on them. It is possible those friends have unknowingly given this or other malicious applications access to their Facebook accounts.