I’m very sure that if I saw a deer coming in through my doggie door, I would be the one frozen in headlights.
I don’t think that grabbing my phone to catch a video would even cross my mind.
I imagine, though, that as soon as I recovered enough from the initial shock I would gain enough of my senses back to do something. But what should you do? It would seem that, though this does tend to happen on occasion, it’s not
The cat door is a very convenient thing. The cat can walk in and out whatever it wants. It makes the pet free, It does not depend upon the owners and feels much better in comparison with other cats and dogs which are devoid of this chance.
However, sometimes the surprises can occur if the house is located in the countryside and is provided with such feature. When cat returned from walk, the other animal followed it. It was unexpected and rather funny!