You see a thread that wants to loiter from some horns and you would be correct to assume that it would hang vertical. The thread wants to loiter and hang from one of the horns. When things hang from things, they usually hang vertical, so that’s what this thread is going to do.
For some reason, Channing Tatum (たて) is strangely attracted to vertical pieces of hanging thread. Channing Tatum starts batting at the vertical thread like a cat.