Renata, please try this:
To understand the concept of twirling the seams at the intersection, cut four squares of fabric to practice with by making a very simple four patch block.
Make two of the squares with dark colors and two of them with light fabric.
The size doesn't really matter for this example, just cut four squares that are the same size....maybe 3"?
Sew two sets of two squares, each pair made with one dark and one light square.
Press the two seams toward the dark fabrics.
Nest and pin the seams securely for the third seam like Laura showed in the video of the quarter-square block.
Stitch the seam and heat press it.
Open the block and from the back carefully remove the stitches from the first two stitched seams that are now inside the seam allowance created by the third seam.
This will allow the seam allowances to ALL be pressed in a clock-wise or counter clock-wise direction, depending on the orientation of your blocks. That is your swirl! Press it well. The front of the block should be a perfect intersection and there will be very little bulk.

Basically, this is falling back on hand piecing principles where we only sew the part of the seam that is apparent from the front of the quilt, and there are no stitches in any of the seam allowances at the intersections so that each seam can be pressed in any direction. When we chain piece our patches we loose that ability.

Hope this makes it easier for you to understand.