Leaking clear liquid out of the back bottom of the car?

The video didn't show up. Are you able to see underneath and be more specific as to the location? The first thing that comes to mind is condensed water vapor from the exhaust. That is a normal result of a properly running engine. Often the manufacturer will drill a tiny weep hole at the bottom / rear of the muffler so that water can escape. On long drives that hole isn't necessary as the exhaust system will get hot enough for that water to evaporate out. It's on the shorter drives when that water sits there when there's no weep hole and can lead to corrosion.

If the vehicle has a rear heater, there can be a heater core and hoses going to it. Those will be along one side, somewhere around the rear half of the vehicle. The two clues for this are the fluid is usually red on GM vehicles, not clear like you described, and the coolant level will drop over time and you'll have to add periodically.

A very common cause of concern is water dripping right under the area of the front passenger's feet. That is from the "AC condensate" when running the air conditioning. Most of the comfort comes from removing the humidity from the air. It condenses in the dash, then drips into a pan and out a tube, onto the ground. That will be clear, but it will only occur on humid days when the AC is running. The AC compressor does also run when the heater is in defrost mode.

Dandy video. That looks like the bottom of the muffler. When the engine is running properly, the byproducts of clean combustion are carbon dioxide and water vapor. With the muffler way at the back, the water vapor has a lot of time to condense by the time it gets there. My suspicion is you won't see that dripping right after a rather long run at highway speed, but if you do, there's still nothing to worry about.

Very happy I could help. I only know three things, and that was one of them. Please come back next time you need our wondrous wisdom.