You worked it out because it repeated. I did not have that opportunity.
You didn't even try. Because you don't want to. Because you prefer the cosy little illusion that you have found something, anything, inexplicable.
The difference between us is that you immediately responded with "Ghosts" and left it at that, whereas I responded with "What's going on here? Let's find out".
You preferentially settled for the first answer you liked. I did not.
You decided on the basis of nothing to believe in something you made up out of whole cloth because you liked it. I decided to nail the actual cause.
I put in the effort to determine a cause, you could not be bothered preferring instead to leap wholeheartedly to an unjustified conclusion simply because you liked it.
I am sorry if this gives you grief, but those are the facts. You have an unexplained sound and that's it. I had an unexplained sound and determined the actual cause by sheer effort and attention to detail. And EVIDENCE.
Were I of your frame of mind, I could genuinely have recorded those sonorous steps and posted them on the web, except there wasn't one back then. Were video as easy as it is now, I could have recorded objects apparently spontaneously moving in my bedroom, but alas such facilities were not available at the time. I had to make do on my own.
So, I went through some sleepless nights waiting up for the event to happen and sure enough, eventually it did happen. Sonerous footsteps transpired. Because I was wide awake waiting for it for the first time, I immediately identified it was coming from the wardrobe.
Next step, repeat with the wardrobe left wide open. Imagine my surprise when the hangers in the wardrobe apparently started spontaneously moving of their own accord. It was like watching the internals of a piano playing. WTF?
Some inspection revealed that only empty hangers moved. Why would that be?
So, out of curiousity, I simply swung an empty hangar. It clonked against the backboard of the wardrobe. close the door (as much as possible) and repeat
and discover that the backboard acts as a soundboard and the body and cavity of the wardrobe acts as a resonance box much like a guitar. Aha. Something must be moving the hangers, but only the empty ones to generate the sound.
Now what would be so lightweight so as to only move the empty hangars?
By pure luck and many sleepless nights, I had my answer. It was a mouse. He had somehow determine that the best route through my bedroom was across the hangars, but at the rear where he could not be seen. The only hangars that move enough were the empty ones, they clonked of the back and the entire wardrobe resonated in a very dramatic way.
One mousetrap later, no more footsteps.