Hey dude, you could try to do this with a combination of Token Identifiers. You could try this until someone comes up with a $regex() pattern, but this seems to work for me.

I've put it in a little alias to show you whats happening.

Code:
alias post {
  var %string = Blehblehbleh got posted 16d 5h 42m 12s ago by blehbleh..
  echo -a $gettok($gettok(%string,$+($findtok(%string,posted,1,32),-,$findtok(%string,ago,1,32)),32),$+(2,-,$calc($numtok($gettok(%string,$+($findtok(%string,posted,1,32),-,$findtok(%string,ago,1,32)),32),32) - 1)),32)
}


Obviously, %string holds the "Blehblehbleh got posted 16d 5h 42m 12s ago by blehbleh.." but this should give you an idea on how to manipulate it.

Then just echoes it back basically.

-Andy