Greasy Fork is available in English.
Adds a download button to the video player.
Thank you for your report! :)
Haha, when I released the previous version, I suspected this might happen sometime. ;) The script simply picked the first file in the list of streams, which happened to be the highest quality stream when I tested it. From version 0.2.3, the streams are inspected and sorted by quality. This should fix the bug you mentioned.
Sorry for being short of time, I know this script deserves more maintenance.
Sometimes download defaults to lowest quality
Test video:
https://vimeo.com/174544848
It downloads the 360p version, not the 1080p one
Tested with both Firefox (GreaseMonkey) and Chromium (Tampermonkey) on Ubuntu 14.04