1. Usually, clusters have the format of blogs, but that’s not the exclusive option: they can also be an infographic, a video, or a podcast. What really matters is that each cluster needs to be organized around the main keyword and solve the user’s problems and provide valuable content.
As far as SEO is concerned, Video content and SEO work together to provide your brand higher visibility. All you have to do is make sure that your video content is both “shareable” as well as “linkable.” Provide consistent and informative content that compels people to share and urges publishers to link to. Your video content needs to be high-quality, engaging, and relevant to the audiences to get the most organic growth.
2. Landing pages are created particularly for a marketing or advertising campaign. So, using a landing page as a subtopic will perhaps not be a good idea. However, the vice-versa can prove to be much more beneficial, i.e. creating a landing page for a subtopic.
Further, adding video to your landing page is one of the most efficient ways to boost engagement and conversion rates. And, using videos (especially the videos from YouTube) in your content is the best way to rank better.
3. I am assuming you are perhaps talking about the landing pages. You can either have a visible landing integrated into a website by simply adding them into headers, footers, or other menus, or a “hidden” landing page, made accessible only through specific ads or links that intend to direct the visitor through a set exploration path.
SEO works the same way irrespective of whether your landing page is visible or hidden.
I think SEO works on only those pages which are already indexed in the google. And I don’t think if you hide something on a site readlightnovel.info that will give a positive imapact on your site, infact this may impact negative on a site.