Observer

Is there a way to make a player, who isn't exactly a player, only want to watch the game, but i want to give her a vision on players only. I use dynamic lightnings, and players don't see each other if they behind the wall. Is there a way to make something like "observator mode"?

Easiest way would be to give the "Observer" control of all the characters, along with the people who are actually playing them. Then she will see everything that any character can see. Just warn her not to click around on the map, otherwise, she might inadvertently grab a player's character icon and move it. 

Another way is to stream it from an observer account that has control to all the characters and let the player watch the stream.

You could create a transparent token image and give them exclusive control of it.  Set vision to extreme levels but make sure the option to be seen by other players is disabled.  They should be able to move the token around where they like without revealing anything to the other players. That said, I 2nd Pat S. suggestion ;  streaming Roll20 games on twitch is remarkably simple and easy to do.  Just make sure every player is OK with it.

With this transparent token is a good option. I'l try it. Thanks