"I will try to do this everyday but I hope people don't write comments just for the sake of writing comments"
No, they really don't. That would not make sense. They mostly do it for attention/visibility and money.

"One thing that everyone should understand is that writing comments that are not genuine and/or full of "empty" words also make a platform look bad."
You are right. Steemit is a perfect example for this. Just see the "nice post" and other spam and spam-like comments under many posts.

"If you don't have much to say about a video after watching it, maybe "nice video" is all you need to say."
No, you don't. You really don't. That is the same as the above mentioned meaningless "nice post" comment.
If you don't have anything nice, funny, constructive, positive to say, then don't say anything.
If you like the video/post/comment, but you can't/unable to or don't want to express your opinion with words, then just upvote the video/post/comment.

"It's not engaging or constructive, but it is better than being fake by unnaturally trying to engage with others."
No, it is not better. Saying "nice video" or "nice post" is actually being fake by unnaturally trying to engage with others.
Or to be more precise, faking/pretending engaging with others.