Material - Panner X TexCoord makes weird ripple and I don't know why

Made the material below with basic knowledge. No idea why this works.

It creates a sort of ripple looking effect that passesalong the path of the panner.
It stops at this point and the UVs continue to expand? (the texture gets smaller) and this effect does not reoccur unless restarting the level.
Video of the Material

Also images




After several minutes it appears like this

I’d love to understand why this works. If you could explain or point me in the right direction that would be much appreciated.

Obviously the UVs are being multiplied over time, hence the eventual tiny textures.
I have no idea why the original ripple is taking place.

Ideally I would like to understand how to make this less of a temperamental effect. I assume it would involve some kind of clamp?