Saying "check" is not required. In tournaments
Why is saying "check" required in the first place?
Saying "check" is only an unofficial "rule" that casual players erroneously think is a requirement. It is kind of like the "house rule" in monopoly that places on the "free parking" space all of the money paid in fines (luxury tax, chance, community chest). It is a very common "rule" that is not in the official rules.
Saying "check" is to alert the other player that he is in "check".
If he does not know that his King is in check and if he moved another piece, can I take the King?
No, you cannot simply take the king. Touch move, however, does apply and often results in a player being forced to either: block the check with the piece they touched even though that piece will not be defended and the check will be immediately renewed; or to capture the checking piece with a more valuable piece even though the checking piece is defended. Also, generally two minutes are added to the opponent's clock and if you make too many illegal moves it is an immediate loss of game (in blitz, depending on the rule set, as little as one illegal move loses whether it is leaving the king in check, moving the knight on a diagonal, playing Bb2xh7 instead of Bc2xh7, castling after the king already moved, or any other illegal move).
Assuming Mario is from Thailand (as indicated by the flag) it is quite understandable why Mario might not have seen them.
Oh, please.
They pirate all the movies.
First, it is not so much whether or not a movie is pirated, but rather whether or not a movie is compatible to a person's culture. I'm not much into foreign films because their style is usually a bit of a mismatch to my cultural views. I don't expect everybody to watch the movies made in my country.
Second, of your list I've only seen "Saving Private Ryan". You didn't include movies I appreciated like "Patton", "Apocalypse Now", "Good Morning Vietnam", "M*A*S*H", "Valkyrie", "Pearl Harbor", "Hacksaw Ridge", "Midway", etc. To say nothing of the unforgettable "Abraham Lincoln, Vampire Hunter".