It's pretty rare that we can use the word "lucky" when talking about a hit-and-run, but that's just the case with this particular one.

Watch as this guy on a bike is struck by a truck driving by, throwing him from his bike.

But not to worry, Mr. Biker!  

That truck that just hit you also happened to lose a mattress it was carrying just as it passed by you! The mattress then lands on the ground and catches the falling biker.  

What luck!