In addition to your phone’s front- and rear-facing cameras, you now have another source for your Vines: you can import existing videos from your phone. From the capture screen, you’ll see a new option in the bottom left corner that lets you import a video. You can select one video or mix together several — and yes, slow-motion videos are supported.
You can also edit Vines faster and more precisely by tapping the scissors from the preview screen. There are new tools such as the duplicate, mute, and preview and undo button.
Tapping the wrench from the capture screen lets you access a second layer of camera tools: grid, plus a new level; the focus lock, which now works with the front-facing camera in addition to the rear-facing camera; ghost mode, which shows you the last frame of your previous shot (helpful for lining up shots); and a new torch feature, so you can now shoot in low-light settings.
Check out the video below for more details. You can download Vine from the App Store for free.