Fascinating viewing but that pilot's judgment was appalling. If it had been a real bomb he and his crew would be dead (on the real raid one store hit a dam in similar circumstances and went off immediately, taking out the Lanc that had released it); as it was, the splash on the live drop alone must have come pretty close to taking his tail off.
The Lanc that dropped the Upkeep that exploded on impact with the Eder Dam (AJ-Z, flown by Sdr Ldr Maudslay) was damaged, not destroyed. Though the damage mot likely resulted in the aircraft having to limp home as far as the German/Dutch boarder, where it was shot down by light flak. In fact I do recall reading somewhere that Maudslay was flying one of the aircraft in footage of the two Lancasters being hit by the water splash from the released Upkeep when senior 617 crews practiced with the weapon a couple of days before the raid.