Sounds like a military helicopter conducting nap-of-the-earth ultra low altitude training exercise.
Most probably a UH-1 Huey, British Lynx or Puma, or a UH-60 Blackhawk.
Crouching figure would be the crewman/door gunner.
Attack/recce helicopters like hiding behind trees etc to hide from their potential targets.
They are relatively slow and pretty noisy so their best means defence is to use the terrain to avoid being seen.
Sounds like it did a pretty good job of avoiding being seen by you.
A lot of this goes on around the huge Suffield training area in Alberta and probably other areas of Canada too.
https://youtu.be/3F_KGgMwRMM