Safari Video Downloader Plugin

The.mp4 files are opening/playing WITHIN Safari, not in QuickTime Player 10.0. Obviously they're using a QuickTime plugin within Safari, but they're still playing within Safari. I want.mp4 files to NOT open in Safari, and instead download to my Downloads folder like most files do.

Once installed simply visit any Youtube video page and you will have 'Save Video As' option to directly download the video in your preferred quality right on the webpage.
If you’re travelling or without internet then you can use Safari video downloader for Mac and easily download videos on your devices. No need to install apps or plugins - just a couple of scrolls and clicks and you’ll have your video (s) stored on your hard drive, ready to watch any time, anywhere.
Works really well. Sometimes there are hiccups with download but that's probably at the server end. The use of mhtml means everything is is held in one file per chapter. Currently links still point to safari books. One important addition would be to remove the href references to safari, replacing it with the local directory.

Enhance and customize the web browsing experience on Mac, iPhone, and iPad with Safari Extensions. Using powerful native APIs and frameworks, as well as familiar web technologies such as HTML, CSS, and JavaScript, you can easily create Safari Extensions in Xcode and distribute them on the App Store in the Extensions category or get them notarized for distribution outside the Mac App Store. And now, Xcode 12 supports the popular WebExtension API and includes a porting tool to make it easy to bring your extensions to Safari.

Blocking Content

Give users the ability to block certain content types on Safari on macOS and iOS. Built with Xcode, these app extensions are designed for speed and don’t slow down browsing. And because extensions never see what webpages users visit, user data is protected.

Extending Apps

Extend the web-browsing experience by allowing Safari to read and modify webpage content on macOS. Safari App Extensions are built with Xcode and can communicate and share data with native apps — so you can integrate app content into Safari or send web data back to your app to create a unified experience.

Distributing Extensions

App Store

The new Extensions category on the Mac App Store showcases Safari extensions, with editorial spotlights and top charts to help users discover and download great extensions from the developer community. When your Safari Extension is ready to be released, upload it to App Store Connect for distribution on the App Store. Apple reviews all extensions and updates to ensure they work reliably. Before submitting for review, make sure to read the guidelines for extensions.