I have heard a great many ghost tales and stories that appear to be psychic predictions. The trouble is:

If you go walking outside barefoot, how many stones will your feet pass over? Or will you only notice the sharp ones that get your attention?

In many cases in my own life where I have heard that "So and So" has this 'ability' I would pay attention to how often they were wrong. Which was VERY often. But when they get something Right- or even CLOSE to right, folks pounce on it and lift it up and put it on a pedestal.
Statistics demands they will get predictions right at some point.

If I asked how often your brother incorrectly predicts or describes something- could you even answer? Probably not. you WANT to believe and you won't pay attention to when he's wrong.

Secondly, even when he's right- how right is he? How right is "right enough"? Your first tale mentioned that he described the man. Was his description of the man accurate? You said yes, yet only gave about three details. I could 'guess' and hit an accurate prediction just on statistics and have done so Many many times. Yet, I am not psychic.

Similar to many beliefs that require faith, what you are describing is based more on a want to believe than on any actual facts or science. Understanding even a little science demonstrates the futility of believing in ghosts or souls. But there is an interesting facet to human nature. This facet is that even though we are already Unique with our heightened intellect, humans, throughout history, have tried to embrace beliefs that give us a privileged or special place in the Universe.
In early days, the Earth was the Center of All Creation.
Only Humans Have souls. Etc etc.
Is that justification for the fact we never see animal ghosts?

Ghosts are like fairy's, goblins, gnomes, elves, demons and angels. Believers come up with lots of convincing tales of personal experiences that don't add up to anything more than the believers imaginative desire to justify a belief.

cosmicdave, the trouble is not that you can or cannot prove the existence of ghosts. It's that you can't even test it in any way. there is Zero- None - Zip - Zilch evidence of ghosts and yet, you will believe anyway. Only because that is your desire. Your mind's already made up.