Sounds like a stuck start valve ( allows air from the APU, auxillary engine in the tail) to turn the engine until it gets to a certain rpm before ignition then fuel is introduced so that the engine can self sustain. The valve can be actioned on the ground by the engineer via a door on the side of the engine.
The noise you heard was probablly the transfer pump between two of the three hydraulic systems, and can sound (or does to me), like a dog barking in the hold. The Power transfer unit works when both engine master swithes are put to on during the engine start (on the ground) till both hydraulic sytems reach the same pressure, so i'd guess that was the sound you'd heard.
All perfectly normal and nothing to be concerned about.
Hope that helps
FBW