There's a flaw, I think, in the nature of the question: cinema and TV are types of literature. I teach a class called Film Literature. They're not great literature, but literature nonetheless. (Video games, I'll give you, are not literature).
So, you're saying, "Does low-grade mass literature impede or enhance literary studies?" A bit of circular logic, no?
They're all part of the study of literature. Visual mass media influences the mainstream culture in ways unimaginable. Young people are born into it. It shapes their worldview. Students must move through the visual to get to the written. The early visual literature is synthesized into the written literature. You can't distinguish them once they're all swimming around in there together, can you? So, how can they enhance or detract each other? It's like saying what you see detracts from what you hear.
Early cinema influenced the modernists this way. Steinbeck, Faulkner, and Camus were all influenced by silent film and early talkies. Visual rhetoric is very powerful. Cubist painting, for example, lead to much of Faulkner's free-style narration and use of stream-of-consiousness. Lately, mass media has creeped into the graphic novels and fictions of young novelists (e.g., Jonathan Safran Foer's Extremely Loud & Incredibly Close).
For further study, you should read the chapters on the written vs. visual in Annie Dillard's The Writing Life. She says:
The written word is weak. Many people prefer life to it...Film and television stimulate the body's senses too, in big ways...The printed word cannot compete with the movies on their ground, and should not....Why should anyone read a book instead of watching big people move on a screen? Because a book can be literature. It is a subtle thing--poor thing, but our own.