  Video grounding aims to locate the timestamps best matching the query
description within an untrimmed video. Prevalent methods can be divided into
moment-level and clip-level frameworks. Moment-level approaches directly
predict the probability of each transient moment to be the boundary in a global
perspective, and they usually perform better in coarse grounding. On the other
hand, clip-level ones aggregate the moments in different time windows into
proposals and then deduce the most similar one, leading to its advantage in
fine-grained grounding. In this paper, we propose a multi-level unified
framework to enhance performance by leveraging the merits of both moment-level
and clip-level methods. Moreover, a novel generation-guided paradigm in both
levels is adopted. It introduces a multi-modal generator to produce the
implicit boundary feature and clip feature, later regarded as queries to
calculate the boundary scores by a discriminator. The generation-guided
solution enhances video grounding from a two-unique-modals' match task to a
cross-modal attention task, which steps out of the previous framework and
obtains notable gains. The proposed Generation-guided Multi-level Unified
network (GMU) surpasses previous methods and reaches State-Of-The-Art on
various benchmarks with disparate features, e.g., Charades-STA, ActivityNet
captions.
