How can I download a video off Safari 9.1? (not YouTube) How can I download a video off of Safari 9.1 and export it into iMovie?
The video is not from YouTube.
Another option is to use keepvid, which has support for many sites. All you have to do is enter the URL for the site containing the video, and choose the output you want. You can also choose to get the video or audio only, and this does work for YouTube. 

This works with almost all modern browsers, no extension required.