This userscript adds a simple download-link to Vine.co video pages.
Even 6 seconds of gif-like video might be worth keeping...
How to make it work
Currently the download button appears on "single post" pages only.
To view a single post, from a user's stream of vines, first, switch to "Timeline view" (button on the left, the default is "Grid view"). Then, click the three dots in the upper right corner of a vine and open "View post page" in a new tab/window by visiting this link with a right-click (or similar on other systems). It's important to do a full page-reload with the "view post page", as vine normally updates only sections of the page and the Add-On will not be able to add the download button then. If you do it with a full "reload", then you'll find the download button, on the upper right corner of the screen. Sometimes it's a bit hidden behind the top header.
-- brought to you by the nice people at Lumerias, your video search engine.
For Instagram, there's our Instagram Video Download.