I've been doing that for almost 20 years. I read it in a side bar magazine item. The "trick" was for getting old plugs out of nasty old engine blocks but I can tell you it works on anything that's fire safe. I've also used it to remove small screws from detail items that won't budge. Perhaps not fire safe, but a heat gun and care will push enough candle wax to get em out as well. I have some straight paraffin bars, and it's helpful for sure, but for some reason candles work better. Mrs Highlander loves candles and always saves the "bones" for me.
There are a lot of farm fix videos associated with that one, I forgot about using bread or tissue paper to remove pilot bearings, thanks for posting it.