OnePlus One just posted a PDF of their April keynote slide presentation for people to download. It's 112 pages, includes every slide from the presentation, and is fairly large at 160MB. There is no audio or video, but if you didn't see the keynote you might be interested in it.
Direct link to PDF:
http://oneplus.net/downloads/presentations/oneplus-one-keynote.pdf
Forum post:
https://forums.oneplus.net/threads/download-oneplus-one-launch-keynote.12240/
Direct link to PDF:
http://oneplus.net/downloads/presentations/oneplus-one-keynote.pdf
Forum post:
https://forums.oneplus.net/threads/download-oneplus-one-launch-keynote.12240/