I've had the best success with lash-it as opposed to zing it for a ridgeline. I also prefer the rl to pass under the tarp (you've seen my rig). Just seems to perform better for me. And no, it has never got me wet. Between the prussik and the carabiner, there seems to be enough of a waterbreak/dripline effect.
Also remember that lash it and zing it are hydrophobic (don't absorb water and actually float), so water transfer is not as big an issue as it once was with the older style lines.
Especially with large tarps, like your Hinterland condo-deluxe, I'd suggests a stouter rl. All those guy-out points are pulling the tarp/rl at around (hypothetically) 20-30 lbs each. Times that by four, six, or eight tie outs and the forces are getting large. Add some wind force into the equation....well somethings gotta give. Spreading those forces equally across the entire tarp fabric ridgeline (with an under the tarp rl) and not on only the two rl tieouts works best for me.
Try adding another wrap to your prussik, it did wonders for me. I now do four wraps and it holds great. (not sure what you had in the video)
Don't always look at the rl as the problem either. In perfect soil, the stakes hold true all night. But once the rain starts, the soil conditions change, and the stakes can shift a few degrees. That can effect the tarp tautness as well.
Its a balancing act to get the tarp right, but not so tight and firm that it rips. Id rather have the tarp sag and move, or have a stake come loose under extreme conditions, than have it fail/rip. I think of it as a failsafe.