Looks to me as if that smoke is coming out of the engine exhaust - possibly because the pilot has pulled the hell out of it trying to recover.
The floats are activated by a small pyrotechnic squib but it would not produce smoke like that. Sometimes the floats are packed with chalk powder to protect against chafing and that can make a cloud of dust when you pop the floats but it does not look like that either.
I think that the engine has been massively over-torqued / over-temped and the smoke is the result of that.
Lucky / skilful recovery.
Looks as though perhaps the underslung load or the longline became snagged?