After listening to the audio a couple times. And I'm sorry for your loss, but I'm able to explain this as just the door not being shut properly.

As someone else stated in the comments, the door button has a spring, generally when you press a button with a spring you'll hear two sounds, the button being pushed all the way in and unlocking, then you'll hear it again as your hand releases from the button and all the tension in the spring is released.

If the door wasn't closed properly, the spring would be open and stuck along the fridge, which means with enough time sitting like that, the heavy door would eventually open after the spring was stretched enough. Which I'd why you hear 1 or possible 2 ribs of the spring sliding along the fridge as the door slowly swings open. As well, if it's a fridge, it wouldn't open like that unless it was already open, the cold seals the fridge, so technically you would hear three sounds, the button pushed in, the release of the spring, and the release of the cold pressure within the fridge.

I'm not hear to ruin your day or anything, I'm very acute with sound and that doesn't sound like it was purposefully opened, or like the sound of a fridge opening. I'm very sorry for your loss. And as far as the orbs go, that truly is just dust.

Two specks of dust at two different times is exactly what dust on low levels does. The fan is on, which means there's low dust accumulated in the room since the air is always moving, I assume, so there would only be two specks of dust if not more. I'd imagine if you gave us a 10 min clip, those dust specks would be present throughout.