For LinkedIn Live Video, a primary indicator of success would be user engagement. As a Product Manager at LinkedIn, I would assess success in 2018 by monitoring active users, the average number of videos viewed per user, the average viewing duration for each video, and the engagement metrics for these videos (such as likes, shares, and comments). Additionally, given that LinkedIn serves as a professional networking platform, the production of professional content would be another vital success factor. This would involve tracking the quantity of videos produced by companies, influencers, or individuals for professional use and the level of engagement they generate. Finally, I would also consider user feedback regarding usability to proactively identify any potential areas for improvement or enhancement.