What is the main feature of Vine as a video app?

The main feature of Vine as a video app is that videos are limited to six seconds and replay continuously. This unique time constraint encouraged users to be creative and innovative, producing concise and engaging content that could be easily shared. The looping playback enhanced the comedic and artistic potential of these brief videos, making the app particularly popular for sharing quick jokes, catchy phrases, or snippets of creative work. The structure of six-second clips was pivotal to Vine's identity and helped to foster a community centered around short-form content.

In contrast to this feature, other options highlight video lengths that do not align with Vine's guidelines, such as one-minute videos or the concept of unlimited length, which are more characteristic of other video platforms. Additionally, the restriction of live broadcasts does not apply to Vine, as the app focused primarily on pre-recorded video content within the six-second framework.