Rear road bike Shimano cassette wobbling during freewheel On my road bike with Shimano stuff the rear cassette with all the cogs wobbles when I free wheel it.

It is very much like this video on youtube, except the bike I own is nowhere near as good or as pricey as the bike (my bike is like a $150-200 bike), and the wobbling on my cassette is much worse (I would describe it as oscillating)


                
            

Is this an issue? Is there a way to tighten the cassette so that that it does not wobble?
I've not seen a cassette that doesn't do this, IMO they all do it to some degree as the cassettes floats on its bearings unless the pawls are engaged. Some say it's by design perhaps to aid with gear changes etc. 
I used to have £2000 road bike with custom built wheels that used to do the same thing,  it never caused any trouble even after many thousands of miles riding. 
Unless it's causing specific issues I wouldn't worry about it.