Most likely Cylinder head cracked then blew off thus constant smoke out one exhaust on that cylinder side. If it dropped a valve it will maintain power at 30 inches or barometric but will PUFF Smoke not stream smoke. If smoke trailing from both exhausts it is a blown supercharger drive seal or broken supercharger drive the later will have the engine stop and windmill, if it breaks the front reduction gearbox gear may end up with a run away prop.
With blown off cylinder head you can in emergency keep running the engine at higher power (or barometric if its banging to much with the blown cylinder ) which is what you maybe seeing going on from the Cessna video and the takeoff. It shakes like hell for few minutes but will put out until the piston comes apart, breaks the rod at which time you feather it . Sometimes will run 1 minute sometimes 2-3mins dependent where the cylinder head comes off. Had 8 failures myself with R1830-92 and R2800-CB16s. 1 Master rod, 1 rod, 2 dropped valves the others were cylinder head blew off some through the cowl. When these big radials stop suddenly from seizure other things break and shear it is a lot of mass and moving parts
All my failures on takeoff or first stage power reduction. All at sea level and that was bad enough. Just some technical thoughts but the investigators will advise later.
They did a good job with what they were given on the day, speedy recovery to all..