You got it right there.

During daylight you won't see that much muzzle flash... at night it is quite bright...when viewed from the side or the front.
Easily seen at night from 300+ m

wow, thats alot of muzzle flash for a silenced firearm...neat vid though.

flash
 

I think that part of the reason there is such a big flash in the movies is because they are using blanks and there is a lot of powder in them. also because it looks cool!
now days they digitaly ad in almost all the sounds and flashes from the guns! if you look on some movies you can even see where they forgot to touch up the gun and you will see that the barrel is solid. most of the guns are rubber however they use airsoft guns some of the time.