In short
Distinguish a video’s progression from a concept’s adoption: velocity compares view observations, while concept momentum compares usage across two periods. Check dates and coverage before interpreting either. A missing value does not equal zero.
Read video velocity
Velocity requires two compatible observations at least six hours apart. It uses the change in views and elapsed time. A missing value means these conditions are not met.
In Discover, use the Velocity filter only if you accept excluding videos without enough history. Also check the collection date.
The measurement concerns growth between observations, not total views divided by hours since publication. Two videos with the same total can therefore have very different velocity depending on what they gained recently.
Read concept momentum
Open Concepts, then a detail page. Momentum compares two seven-day periods covered by account monitoring. It describes change within that observed scope.
Account momentum describes something different again: changing velocity for the same videos across two measured weeks. Do not confuse that percentage with concept momentum. In available tooltips, review the period, sample counts and coverage to identify the comparison you are using.
Put the three signals in perspective
Fictional example: a counter rises from 20,000 to 26,000 views across twelve compatible hours. Observed growth is 500 views per hour. That calculation does not say whether the same rate will continue tomorrow or whether the views come from different people.
For a concept, moving from ten to fifteen analyzed posts across two covered weeks represents +50% observed adoption. Each video’s counter could still be slowing down. Read velocity for an individual post’s movement and concept momentum for how frequently an idea is used.
Understand a dash
Without comparable history, sufficient coverage or a nonzero previous period, the calculation may be unavailable. A dash does not mean 0%. Rising velocity for one video does not establish that an entire concept is growing.