How Hard Is It To Train A Wild Cat? Or Can You

Where my mum lives there is lots of feral cats and when I went and stayed with her for a few months, I managed to catch a kitten in a possum trap with a bit of sausage. The only way I could hold the kitten for the first week was by wrapping it entirely in an old towel so it couldn't claw me and it was dark and so the kitten was submissive. Eventually I could hold the kitten, still in a towel with its head uncovered so it could see. I always held the kitten close to my chest so it could feel my heartbeat. After a while, I didn't need the towel to hold the kitten at all and I could often pick up the kitten without cornering it and I could pat it freely. My step father gave it to the daughter of a family friend and she treated it like a normal kitten and all was well. Except one day, feral instincts kicked in again when it was let outside as it normally was in the morning and it didn't return like it normally would. The girl kept the kitten as a pet for a few months buts its borne instincts took over and it went back to being a feral cat.
I wouldn't even bother trying to tame an older feral cat. It's a little too late for them I'd say but the kitten I caught (who was about 8 weeks when I caught her) was at the right age to try to tame.
There is a video getting round on Facebook and Youtube about 2 Englishmen who bought a lion cub from Harrods, raised it and released in to the African wild and years later when they went to go see it, it still remembered them and wanted to play with them despite the fact the cub was now fully grown and had his own pride.