Nothing worse than full bad box.

For sure something is damaged. A healthy engine will have a light flow of air & vapor out the breather, not puffing smoke.

The volume in the crankcase does not change as the pistons go up and down. For each piston moving down there is one moving up. Any flow out the breathers is from combustion gases getting past the rings or piston.

https://www.aa1car.com/library/engine_blowby.htm

Just for grins crank the engine with the ignition off for a few seconds. You can tell by the sound when a leaky or dead cylinder hits the compression stroke. Once you learn that sound the only reason for a compression test is to figure out which one (or more than one) are hurt.

Unfortunately no. According to him it was previously owned by a marina owner who absolutely loved the boat and bought it brand new and that's who did the full build on it. He only owned the boat for maybe 3 or 4 months and only put 2 hours on it before realizing his wife and 3 kids were a bad fit for this little boat so he sold it to me.

What further damage could I do exactly?? If the piston or pistons are already screwed, i assume it couldn't get much worse?? Maybe, well probably, I am wrong here.

If it were me id first start with a compression test...and if that doesnt point to one or more piston holes to look at i would then do a leak down test and make the call from there.......that smoke coming out of the valve covers reminds me of a steam locomotive! sorry dont mean to hit a guy if he's down....just making light of it

whats the oil pressure ? sounds like a bunch of rockers rattling, I wouldn't run it till the valves are adjusted properly

Gauge says its right around 70- 80 but that's rather hard for me to believe.

when you started it in the video did you have water hose hooked to the engine ?

I think the boat is in the water Ken.

At this point i dont think you'll do any more damage to the piston or cyl walls then there is all-ready....if oil pressure is good and the motor will stay running and its not making any bad knocking noises then i say go for it to the launch ramp...
I once threw a piston and rod out the bottom of the engine cause the builder forgot to tighten one of the rod cap bolts....other then the fact all the oil was gone and it was shaking a little bit the motor still ran! i drove it home at idle for 3hrs to the launch ramp on the other engine then started up the hurt motor at the dock to load it on to the trailer! I was shocked

that things making more noise than a 8V 92 detroit