  What makes content go viral? Which videos become popular and why others
don't? Such questions have elicited significant attention from both researchers
and industry, particularly in the context of online media. A range of models
have been recently proposed to explain and predict popularity; however, there
is a short supply of practical tools, accessible for regular users, that
leverage these theoretical results. HIPie -- an interactive visualization
system -- is created to fill this gap, by enabling users to reason about the
virality and the popularity of online videos. It retrieves the metadata and the
past popularity series of Youtube videos, it employs Hawkes Intensity Process,
a state-of-the-art online popularity model for explaining and predicting video
popularity, and it presents videos comparatively in a series of interactive
plots. This system will help both content consumers and content producers in a
range of data-driven inquiries, such as to comparatively analyze videos and
channels, to explain and predict future popularity, to identify viral videos,
and to estimate response to online promotion.
