OTT stands for 'Over-The-Top' is a term in media industry for the delivery of film and TV content via internet. It doen't require any users to subscribe to a traditional cable or satellite pay TV service.
Examples for OTT players include Netflix and Amazon Prime.
In the mesh topology, each computer is connected to the other with a separate physical link in a network. It is most reliable topology as the network does not get down in case one of the nodes is failed.