As was mentioned, this has been done for many years. And, it has been discussed in the various on-line forums I frequent fairly often.
I played around with this about 20 years ago. I didn't read the link you posted, but I am sure whatever their technique is for loading will work fine. I found wax bullets to be very accurate and functioned fine out of revolvers. I didn't try them in any autopistols. There is no mess to clean up. There is no "cooked" wax in the barrel and chamber. When you recover the bullets they are intact and do not melt to any degree that I could see with the naked eye.
I wouldn't really advoate shooting these indoors: this is what I intended to do with them. First of all, they are louder than you might think. Second, there is more smoke than you might think. Lastly, it is my understanding that breathing the smoke from primers is a good way to ingest lead.
They would be fine for shooting in the yard, or maybe even the garage in a semi-rural area.
You know the rest. In the books you have read
How the British Regulars fired and fled,
How the farmers gave them ball for ball,
From behind each fence and farmyard wall,
Chasing the redcoats down the lane,
Then crossing the fields to emerge again
Under the trees at the turn of the road,
And only pausing to fire and load.