One of the scenes in that video has a sprite in Alpha mode. The white corners are 100% solid while the rest of it is semi-transparent because it's not a maximized 255 RGB value.
You need to repaint the white parts to 100% black (meaning, 0,0,0 RGB) and then load the sprite with the Masked flag (4, just 4, and nothing else. Perhaps 4 + 1 if you really wanna be precise of what you are doing).
That should work. Remember, it won't change anything if you don't paint the white parts black. You really need to this in order for the Masked flag to work.
You need to repaint the white parts to 100% black (meaning, 0,0,0 RGB) and then load the sprite with the Masked flag (4, just 4, and nothing else. Perhaps 4 + 1 if you really wanna be precise of what you are doing).
That should work. Remember, it won't change anything if you don't paint the white parts black. You really need to this in order for the Masked flag to work.