Unfortunately, the Server doesn't send any information about other players' inventories to the Client, therefore it's impossible to show it in the Replay.
Theoretically, it would be possible to show the recording player's inventory, but the ReplayMod tries to treat every player the same, and we do not plan on changing that.
Thanks for your feedback!
I think there should be a mode where you can have it so it records whats going on around you, and your inventory&mouse so you can render a video as if you were recording, and save a lot of space!