Hmm okay, did not knew it. I just thought it works that way, this is at least how I understood it.
Don't blame yourself for not knowing that. It's not one of the best documented things of the mod.
@CrushedPixel will create a video tutorial for paths/keyframes at some point in which he'll probably also explain how V works. If one of the mods or other users who understands how it works wishes to explain it here in detail, please do so. I've unfortunately not got enough time to do that.