I've been using Video Download Helper with Firefox for several years, and it performs very, very well. I rarely find a video archive that it doesn't work with, and I've hit some fairly obscure ones. The developers do a good job of keeping it up to date. My one complaint is a new feature. When you instigate a download, instead of just popping up a save-as dialogue, it opens a new web page with a list of recent downloads and a "save" link at the bottom. This is clunky and unnecessary. However, I do give it kudos for letting me pick the directory (folder) where I want the files to go instead of defaulting to some stupid Windowws download folder.