Short answer: If you are just using their video, none, they have the copyright. If you are using it for commentary, criticism, parody, news reporting, research, teaching, or scholarship you can use some as determined by 4 fair use factors, like are
Short answer: If you are just using their video, none, they have the copyright. If you are using it for commentary, criticism, parody, news reporting, research, teaching, or scholarship you can use some as determined by 4 fair use factors, like are