The YouTube clip is quite a mish-mash. Most of the shots are taken from the movie 'The Dam Busters' where ( as in WWII ) the Derwent reservoir was used, as Stefan rightly said. Only low-flying practise was carried out there, no dropping of bombs.
Interestingly, look closely and you'll see that the Lancasters are flying at 30ft, not 60ft as in 'the real thing'. When it came to making the film, 60ft didn't look dramatic enough. So the RAF Lancaster crews simply went lower.....
The 'bouncing bomb' footage in the clip is in fact the testing of the 618 Squadron Mosquito-dropped
'Highball' bomb, much smaller than the
'Upkeep' dams mine. These tests were carried out against ships (
Highball was intended for the
Tirpitz ) moored in Lochs Striven and a'Chairn Bain, Scotland ( I fully expect The Historian to leap into his car immediately !

).
The half-size
Upkeep dummy which has gone to Scampton is most likely one of the ones tested at Reculver, Kent and recovered in the 1970s/80s.