will why is there a replay forum and there is already a replay.php place
or thats not the question
why is that tab there when there is already a forum
it is unactive
any answer?

You can share replays in both places, except one of them isn't a forum. You can use what ever one you want to.

Other things you may find intriguing:
There is a mods tab and a mods forum.
There is a market tab and a market forum.
There is a clan tab and a clan forum.

:O