Greasy Fork is available in English.
Replaces built-in Flash player with HTML5
Yes, Anime News Network has a videos section, though it seems to have not been updated since early 2016, and it shows. It was taken off the navbar sometime in 2017, so the only way to get to it is through some pages on specific anime. Plus it still uses Flash-based embeds
The main aim of this script is to replace the Flash-based player used on a small percentage of videos, though it attempts to replace external embeds for YouTube and Hulu where possible.
YouTube's embed URL is switched to HTTPS so that the browser won't block it, and it's made to look like Flash is "okay", and the browser takes care of the rest.
A proper Hulu embed replacement might not be possible, as their HTML5 embed URL is too different from the Flash one.
This script does not replace Crunchyroll's player with HTML5, but I wrote a separate script that does just that (and within Crunchyroll itself) here