The Lancasters shown in the clip are the BII, with the Bristol Hercules radial engine. 300 BIIs were built by Armstrong Whitworth and were used mostly by Canadian squadrons in 6 Group.
The aircraft’s Squadron can be indentified by their call sign letters. 426 Squadron’s letters were “OW” which can be seen on some of the aircraft in the film. You will also see “EQ” on the aircraft at the beginning of the film which belonged to RCAF 408 Squadron. No. 408 converted to Lancasters in August 1943 after joining 426 Squadron at RAF Linton-on-Ouse.