This is the source of background.js for a now-unpublished Chrome extension called "Video Downloader professional" (ID kmdldgcmokdpmacblnehppgkjphcbpnn, since then replaced with another "Video Downloader professional" (ID bacakpdjpomjaelpkpkabmedhkoongbi). This script is republished here for educational / research purposes. It has initially been extracted from the extension’s archive available as v2.4 on https://www.crx4chrome.com/.
The extension has appeared in malware discussions in the past. Its replacement of Video downloader professional "bacakpdjpomjaelpkpkabmedhkoongbi" seems related to the [ownership change of The Great Suspender](greatsuspender/thegreatsuspender#1263 (comment)