Edit: Ok, I'm done arguing! I posted my thoughts and the reasons why I think it's just the tarp slightly moving from the breeze. (Think of a flag waving and the light hitting it at different angles). I'm not saying that she doesn't smoke, just saying that what this clip is showing, isn't what it appears to be. (especially the choppy clips on youtube). Download the HD version and watch it on a bigger screen.
Blue tarp ripple... Just the way the sunlight is hitting the tarp while the wind is blowing. Just look at how it follows the tarp. And how there is no smokes above the blue tarp. Also notice how solid the white is. Smokes tends to disperse. Not stay the same shape.
Again, the 1st animated gifs proves it's not smoke. Just the tarp moving. The 1st person who made the claim of "smokes" was probably a TLC plant. Remember, this is outdoors at the beach where there is usually a constant breeze. No way can the "smokes" stay in that solid state, especially from the distance this was taken. (This is a zoomed-in clip taken from the show).
Notice the "smokes" before Kate turns.
Looking at the above photo, you can see the white "smokes" as they call it, disperse all over the blue tarp. This is showing that the wind is slightly moving the tarp and light is reflecting at certain angles.
Notice how it flows with the tarp instead of dissipating.
If you look really close, you can see that the white "smoke" is actually behind Kate, and on the blue tarp. Since the tarp is at an angle, so is the white "smoke" the ripples across it.