You can call it coincidence but i dont think thats true, i call it bestial instinct. Animals basically have 1 goal in their lives and that is reproduction. They know when its time for that, the female spreads an irresistable odor which tells the male its time to breed. Thats exactly what happens in these clips, the smell of pussy spreads itself through the room and activates the dog. Guaranteed the dogs in this video are male.(i dont have information about the cat in the end...).