It is one of the species of Dodder (Cuscuta sp.).
A parasitic plant that has no roots in the soil and derives nutrients from the host plant.
The yellow hair-like structures are roots and they wave about, until a suitable host plant is found and they will attach themselves to it, by twining around it's stem.

Here's an article that may be useful in establishing control of the weed, before it becomes a terrific problem.

Here is a link that might be useful: Cuscuta (Dodder)