I'm confused.
She's calling him Unc but I thought he was a random guy.
I hope that's a real video because the gestures were very generous. But it seems questionable.
"Unc" is a common nickname, and it doesn't just apply to people you know or are related to. Once you reach a certain age, you become an Unc or Auntie.
For example:
We've been conditioned to think that everything online is fake, but I believe that the video is legit. If you click through the tweet and follow the thread, it really does seem like the young lady was displaying some genuine kindness to a stranger, and she gained a friend in the process.