Thanks for all those responses. For the sound it seems good enough.
I need invisible tokens to do like in the video: when my player point an objet it seems to react, showing a name. If he click on this objet (a book, a scroll...) it opens something else (another image, a note...). The invisible tokens make the player think he is interacting with the object on the image.
I deeply regret that the dice results are not shown if outside the chat box (a standard behavior in other VTTs, visually nicer, with the possibility to have bigger dices, like in roll20 or Foundry). It is possible to roll outside the chat box though, but not starting on an image, it is weird).
Lastly I would have thought you can share an enlarged image. But it is not a problem, the player can choose any size he want. And for the icon bar, it is not a big deal.

