[Inkscape-user] I'm struggling with node selection

Hi! That's my first try with Inkscape and I think I've broken it. Every time I select 2+ nodes with the "Edit path by nodes" tool the critter add 1 other node between the 2 selected. See the little wmv attached :)

I know...I've clicked something not supposed to be clicked :°D

Thank in advance for you help :)