Did he talk about tress?!
Yes, he did

When the whole tree breaks, it becomes a set of rigid bodies and how it falls will be calculated differently for each client.. so the trees wont fall the same way each time, and also how they fall for one client, doesnt nessecarily mean they fall the same for another client. Breakage is synced, when a tree breaks, it breaks for everybody, just falls slightly differently(this is to save network bandwidth.. having to transmit position, rotation values for each piece of broken tree/particle etc every frame to all clients would kill performance..)
After a tree breaks, it is not in sync with everybody anymore. The quote I used before was because of
though all the things that are non synced are not gameplay impacting in any serious way.
Breaking trees may not be impacting gameplay in a serious way, but they definitely do more so than the asteroids on DV (well, which can't impact the gameplay in any way anyway, unless you count the scares that people sometime get

). Breaking trees are just immensly annoying sometimes. What I am getting at is, that they should not interact with the player anymore after they break, since they are not synced with everyone anyway.