Andre would've used boilies which can stay intact for at least 3 days. Boilies will also withstand being picked up and dropped again by fish. Some details here :
http://www.carp.net/carp.htmBait would also have been hair rigged i.e. not on the barb of the hook.
http://www.anglersnet.co.uk/Rig-Section/Carp-Rigs/tie_hair_rig_knotless_knot.html Hair rigging goes back to the seventies and relies on the fact that carp suck bait in and blow it out if at all suspect - the barb catches them when they blow it out.
The owner of that lake , Luke Moffatt , is well known here for both carp and large catfish he's caught too in the both the French and Spanish slow moving rivers. Luke verified the weight. The fish has been caught before at lower weights but above 80lb. It's common practice here to name large carp which are ALWAYS returned to the water : as are infact all carp regardless of size. This one is called The Scar - that's due to a wound which happened when it got tangled in line some time ago.
Whenever I've mentioned carp fishing to American friends they've laughed ! Those hooligans in Canada fish for them with bows and arrows.
If you've never tried it then try fishing on the top of the water for carp. PM me if you want to know how to rig for that. It's huge fun.
edit - BTW the carp would not have been THROWN back. They're treated like babies out of the water and are then very carefully put back.