Kagi provides a fantastic summarizer.

I have a bookmarklet for Kagi's Universal Summarizer, and if a long article or video doesn't immediately tell me "what it's gonna tell me" then I just click it.

  javascript:Object.assign(document.createElement("a"), {href: `https://kagi.com/summarizer/index.html?url=${encodeURIComponent(window.location)}`, target: "_blank"}).click();

Protip: Youtube changed something recently, and now I think you have to show the transcript and watch/wait a little bit before Kagi can find the transcript and summarize the video.