When flash met it's untimely death, the advertising creatives that I worked spent 10 years asking for solutions that involved transparent video in html; we had to tell them no.
I hadn't really considered that browser blend modes have turned that party back on.
I also, on the topic of tech details, make extensive use of the new scroll-timeline stuff which lets you tie CSS animations to the scroll position. it has only landed in chrome at the moment (as of maybe February) so I just use it as a progressive enhancement but it's very cool and performant.
On a side note: many of the pages on the site — with multiple large images, video, and sound — use 1/4th the data than of a standard article on CNN.com without an adblocker, even some with an adblocker.
It was content for the sake of content.
This level of detail, especially when it's implemented in a performant way, really elevates the webcraft here. To the author: nicely done.