Creators frequently see a video's click rate drop while the video is performing well. The decline is a consequence of who is being shown it, and it usually indicates success rather than failure.
Distribution starts with the most likely audience
The first impressions go to subscribers and to viewers with a strong history of watching similar material, because that is where a positive response is most probable.
Those viewers click at a high rate, since they already know the channel and are predisposed toward its subjects.
The early figure therefore measures an unusually favourable audience, and it is not a rate the video can sustain as the pool widens.
Each expansion reaches a less related group
If the response is good, the video is shown to progressively broader audiences, each with a weaker connection to the channel.
Broader audiences click less on everything, so the cumulative rate falls even while the number of clicks per hour is rising.
A falling rate alongside rising views is the signature of expansion, and a stable rate alongside flat views usually means the video never left its core audience.
The rate is meaningless without its context
Comparing click rates between videos with different reach compares different audiences, and the video that reached further is penalised for having done so.
Comparisons across channels are worse, since a channel serving a narrow subject with committed subscribers will show a higher rate at a fraction of the reach.
The useful comparison is a video against itself over time, watching how the rate behaves as distribution changes rather than reading a single number.
Thumbnail changes are hard to evaluate for the same reason
Replacing an image mid-run alters the rate at the same time as the audience is changing, and the two effects are not separable from the reported figure.
An apparent improvement can simply be a return to a narrower audience after expansion stopped, which is the opposite of what the creator concluded.
Meaningful evaluation requires comparing similar stages of distribution, which is why casual testing produces so much unreliable advice.
What the metric is actually good for
A very low rate during the earliest impressions is a genuine signal, because it reports that the most sympathetic possible audience declined to click.
That is worth acting on, whereas the later decline is a description of reach rather than a problem to correct.
Watching where a rate sits at each stage tells a creator whether the video failed its own audience or simply travelled beyond it.