There seems to be a lot of input from Rotorheads with little or no experience of bucket work. A 50' or 100' line with a Bambi is a necessity for many fire ops when the water source is surrounded by trees or other obstructions, and the ability to fly such underslung loads is part of being checked to the line for fire work. As with most loads it will fly in a predictable fashion, full or empty, and a competent pilot will manoeuvre the machine to put the load where it is needed.
The real issue here would seem to be using a 10 metre (33 foot) line, with resultant flight characteristics which allowed it to put the bucket up into the TR. I'll find some photos later which show the way that an empty Bambi flies at the end of a medium length line.