OK, but... Rated 3 out of 5 stars
Easy to use, downloads at a respectable speed, but gives wildly incorrect bitrate information. I've just downloaded a video, 22' 09" in length, from Youtube using this add-on, selecting MP4 360. This should have used roughly 60MB of my data transfer allowance. In fact the bitrate was roughly double the one stated and it used about 120MB. This is a serious defect for the many people who, like me, have a monthly data transfer limit. Could the add-on possibly be fixed so that it does as it's told, or at least tells the truth, about the download bitrate?This review is for a previous version of the add-on (22.214.171.124-signed).
I don't understand your complaint. When you download a video, a Firefox dialog shows the filesize of the video (for example: 30 MB). The extension only finds the URL of the file and Firefox downloads it. That's all.
I'm not sure what software you've used to measure bandwidth, but it's likely that it measured both the YouTube player transfer and the file download. Obviously, the video starts playing and your browser downloads it in the cache.