Question

To create parallel structure in the sentence, which phrase would best replace the words "only landscapes"? Videos that have people in them are more interesting than only landscapes. videos that have only landscapes to have only landscapes in videos having videos with only landscapes only landscape videos

Answer 1

"only landscapes" would turn to "videos that have only landscapes"

Answer 2

The answer to your question would be that the phrase that would replace the words "only landscapes" best to create a parallel structure is the following one: Videos that have only landscapes.

Parallel structure, also known as parallelism, is the repetition of a grammatical construction within a sentence. In this case, the repeated construction is the whole NP (the noun head and its modifiers: videos that have people in them/videos that have only landscapes).