Voting is done by holding up fingers representing our vote. Here zero fingers means veto carry over. One person can veto the whole carryover if they are that uncomfortable with it. One means a vote against the carry over. Two means a vote for the carry over.
All people decide then expose their vote simultaneously.
The first phase is a non-binding vote held before any discussion so we can see which way people are leaning. Next we have a round of discussion. People can argue for their preference, and listen to other's. Andrew says some good words about the positive aspects of committing to a challenging route. Then there is a binding vote.