Thank you sajhamitra for the comments. Like you said video is definitely little dark. I used variable ND filter to control the exposure. I was little concerned about blowing out the highlights and thus ended up with the darker footages. Also I didn't realized about the reflection on the water until I saw your comment. This was really helpful. I will pay more attention on the reflection next time.

I used Sony A6500 and Sony 18-105mm G OSS along with variable ND filter for the video.

Also please check out my new video on another post.