Why don’t people watch things with very high levels of cellulose

Well if you did mean "eat" and not "watch" the answer would beCellulose is a carbohydrate which is present in the plant cells. The cellulose is a polymer with glucose as the monomer units. The monomer units of cellulose is attached by the beta linkages. The cellulose provides structural support to the plant cells by forming micro-tubules. The humans cannot eat the diet rich in cellulose because they lack the enzymes that are needed to digest them. Some animals, such as cows and termites have these enzymes but not the humans. So the answer would be "people cannot digest cellulose".