However, I've noticed that occasionally, when watching videos in full-screen mode, Firefox has crashed and the error reporter has labeled this plugin as one of the culprits, so I do deactivate it from time to time. I've been using this plug-in for some time now and there is little to fault in it - it's definitely one of the best video download plug-ins I've ever used.
If there are several videos, you can download more than one at a time, or just one by one to save bandwidth. To change the format downloaded, just go to preferences, which can be accessed by right-clicking on the icon and choosing 'Preferences'. The great thing is that you can configure the format that you want it to download it in and it works for just about any site with Flash video.
