DTube Question: Reward For Answer

On the DTube platform (https://d.tube/) when the upload button is clicked there are 3 options under 'Choose a source:':

My questions are:

1. If peer-to-peer is selected, where exactly is the file uploaded to and hosted?
2. What is peer-to-peer about it?
3. How are the peers incentivised and/or paid?

If you know the answers please comment below and I will upvote it to issue your reward.

Thank you in advance.