Are you into watching videos? Do you prefer your favorite videos are at your hand any time you want to watch them? In such case Video Downloader is a thing you should give a try to.
The extension is completely optimized for Opera and it is extremely easy to use.
When you install it, you get an icon in the toolbar. To download the video you just start the playback and click the icon - it will grab the url automatically and get the video for you.
File formats supported: flv, mov, avi, wmv (ms-wmv), asf (ms-asf), swf, webm, mp4 (mpeg), 3gp (3gpp)