The "Network probe" settings makes this extension highly reliable in finding the source to download from, though it is VERY CPU intensive, as far as extensions go. Never hits a peak in usage and plateau to a lower consistent usage, instead being the most CPU intensive thing running in my firefox browser perpetually, compared to both active Addons and active Tabs, at least quadrupling the resources required to play a 1080p@60fps youtube video.

But hey, it isn't called Efficient or Performant Video DownloadHelper, so I can't fault them much on that, I guess.