What does this tail tell us?

I am sorry if this isn't the right place for this but I just wanted to know what does this mean when a cat does this the tip of the tail swishes sorta looks like a tiny question mark.

I love that video! I've seen it so many times, such a cutie!

According to this website: http://www.abcarticledirectory.com/A...l-Tells/185669 it means the cat is playful.

More/less its a friendly greeting sign - the cat is relaxed and knows who you are and is happy.

i see so it means the cat is just happy to see you? saying hello maybe?

Tail up, tip moving gently, means friendly and unafraid.

according to The Messy Beast...

[font=Arial,Helvetica]If it is friendly but cautious of the other cat or person, the upright tail is hooked over at the tip indicating a degree of uncertainty.[/font]

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We call that the J tail here.

OMG that video was the cutest video ever

so many different um explanations about it =( I wonder which is fact.
and what does it mean when its doing the same movement but the tail is not up, its on the ground. The tail doesnt hit the ground hard or anything it just looks exactly like that but on the ground not high up. I hope that made sense

once more per The Messy Beast:

When a cat is relaxed, confident and alert, it walks with its tail horizontally behind it or even slightly drooping.

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With mine it means they are excited and/or happy

When my cat does it.

She is usually in a playful mood.

Awwww... what a cute, squeaky little meow!

I see thank you very much

That was absolutely hysterical. I laughed out loud when the scary pounding music suddenly ceased and that little tiny meow came out. Love it.