At least on Safari on OS X, the native browser player lets me download the source video file. The ClickToPlugin extension gives me this native player on YouTube

At least on Safari on OS X, the native browser player lets me download the source video file. The ClickToPlugin extension gives me this native player on YouTube videos, so I find this to be a much easier way to save simple videos. However, this project seems to support way more than just simple downloads. Things like thumbnails, subtitles, and encoding parameters make this a much more involved tool for all sorts of advanced use cases. Cool!