I find it does well with ebooks. I haven't tried with pdfs or videos. The quality of the AndiSearch summaries for the things I use every day like articles, Wikipedia and technical documentation is very good.

The Summarize button is on the search results, therefore you don't need to visit a separate site and paste in the url. Additionally, you already know when a summary is available as the button only shows when it is. It is new but already I feel that it changes how you use a search engine having this feature available right there on the results.

The Kagi one said 'No summary available at this moment, please try again later.' for many of the urls I tried.