I need to play flash video on Facebook but I'm getting this error.
Upon checkng this link, https://wiki.archlinux.org/index.php/chromium#Flash_Player_plugin, chromium-pepper is the solution.
Chromium-pepper-flash is a Google Chrome's Pepper Flash plugin for Chromium (stable version).
1.sudo yaourt -S chromium-pepper-flash
2.Restart the System
Now, the player is working. =)