As after each keynote, Apple has posted the full recording on its website. If you were not there yesterday during the presentation and you understand English, it is therefore possible to view it now.
Without completely spoiling yourself, you will learn more about the HBO Now streaming service, the ResearchKit framework dedicated to health, a 12-inch MacBook Retina, the Apple Watch (read: Keynote: what to remember about the Apple Watch) or on iOS 8.2. The firmware was made available to the general public after the conference.
In addition to viewing the keynote in streaming on the official Apple website at this address (requires QuickTime), it is possible to download it for free in three different formats (SD, HD 720P and HD 1080P). It will also be posted on YouTube in the coming days. Do not hesitate to tell us what you thought about it in the comments!