I’m not familiar with Latvian football, but according to the video below they are very creative in their tactics.

It’s an u17 match between Liepajas Metalurgs (blue shirts) and JDFS Alberts (orange shirts). The blue team is already champion in the league, but they want to try something new. This is their comment posted under the video: “Take it easy, they already were champions, so in the last minutes they tried something they wanted to do all year, but there weren’t chance to do that.”

The players of Liepjas Metalurgs get a free kick and surround the ball with the almost the whole team. After the referee signal, they take the kick and walk slowly forward, not giving any space to the opponents. The Alberts players try to sneak in the circle, but the referee whistles for an offence by one of them. That goes well a few times, but then … have a look!

What’s in the Laws of the Game about such situations? Check Laws of the Game: Fouls and Misconduct (page 113)

Charging an opponent
The act of charging is a challenge for space using physical contact within
playing distance of the ball without using arms or elbows.
It is an offence to charge an opponent:

• in a careless manner
• in a reckless manner
• using excessive force

It’s filmed from a distance, but I think the defenders were making an offence by breaking into the circle. The person who posted the video mentioned that this was something they wanted to do all season. But what should they have taken into account if they wanted the score that way? The attackers should have thought of the fact that they can’t bump into standing players. For the explanation of that you’ve to look at page 116 of your English rulebook (don’t know page numbers in other languages): “All players have a right to their position on the field of play, being in the way of an opponent is not the same as moving into the way of an opponent.” I bet the referee’s whistling because one of the opponents is falling down after the circle bumps into him.

NB: I still got no information about USSF Referee Advices and why they’re not introduced in other countries. But you should at least have a look at the comments below.