These videos would not have human voices. They would show nature scenes with the sounds of birds chirping, elk baying, the wind blowing, insects buzzing, etc.
Some good places to record such videos are the African Serengeti, beaver ponds on Canada, flowers in mountain meadows, the European Alps,
the Mediterranean, the Riviera, water in streams, wild animals, flowers in bloom, and many more.
These videos could be any length but I propose 2 hours to be right as it usually is in most movies.
There are relaxation tapes that record nature sounds. Nature videos could relax people like audio relaxation tapes do. I have seen audio relaxation tapes on sale in drug stores. Videos of outside could be marketed in any store.