Why does my data say that more people watched 75% of my video then did 25% of my video? If you watched 75% wouldn't that mean you watched 25% too?
Video Completion Quartiles refer to the number of video views that made it to the 25, 50, 75 or 100 percent mark of a video. Google Ads defines Video Quartile XX Rate as the "Percentage of impressions where the viewer watched XX% of your video."
However, there is one big curve ball regarding the way that most ad platforms, like Google Ads, track Video Completion Quartiles. To use a bad metaphor, think of each quartile in the video as a trip-wire. When a user crosses over the quartile mark (trips the wire) they set off a reaction that records them making it to that quartile. The tricky thing with trip-wires, though, is that you can jump over them. So, if the user skips over the part of the video with the trip-wire, then they don't get recorded for that quartile. Then when they make it to another quartile of the video, they DO get recorded for that one but remain unrecorded for the prior one that they had skipped.
This effect can lead to some pretty confusing metrics if not fully understood by the analyst. For example, there could, from time to time, be cases where a video has a higher number/rate of 75% video completions than there were 25%. Seems impossible at face value because if you made it to the 75% mark, you clearly made it to the 25% mark also. However, if you get enough users who skipped over the first quartile, they won't get tracked as having made it to the 25% mark. Then if they cross the 75% threshold, then they will get recorded at the 75% mark.