The Bamix 'beater' attachment is just a flat disk which rotates on an immersion blender. When it rotates the disk stays mostly in place, it doesn't displace the liquid in a way that moving a traditional whisk would.
How does that beater attachment work? For example, this promotional video using the attachment shows egg whites from two eggs turn into foam in less than 30 seconds. I have the attachment and contrary to my expectations it's just a flat disk without any ridges to increase friction when spinning around in the liquid.
How does this form of whisking work?