318 diagnosis

Seeing this second video, it looks sorta normal to me..

What Ima thinking, is that your smoke is just water vapor. If you see water dripping out of the tailpipe, that would be normal. But if you don't see it, that only means that the water vapor, if that is what it is, is condensing inside the mufflers, and the exhaust stream is just picking up random amounts of it, as liquid water, and then blowing it out the back.
For this reason, your mufflers should be drilled at the lowest hanging points with small holes, one in each muffler, no bigger than 1/8inch. If smaller than 3/32, the water may not drain at engine shut-off. If bigger, you will start to hear them. Be advised that, if you don't drill holes, the natural acid formation in the non-drilled mufflers will eventually rot the holes for you, and they will be neither pretty nor welcome.
Now, to prevent this natural event is not possible. But you can increase the minimum coolant temperature of your engine to minimize this. And, your exhaust system should be somewhat sloped downhill to the mufflers. If that is not possible, then I would drill the pipes at whatever point is the lowest, and then you can see/watch the steam blow out, lol.
However, if where you live, the atmosphere is naturally humid, you will never get rid of it.
If it is water-vapor, this is probably a sign of a pretty good tune, at whatever rpm it is turning, when you see it. Which, with a Whiplash cam at idle, that would surprise the crapoutta me, lol.
So IDK, that's my thinking as of today.