Pausing a video and taking a screenshot captures your screen, not the video: you get your display's resolution, the player's UI, and whatever the player did to the picture on the way. Extracting decodes the actual frame the file contains and saves that.
Flippy seeks to your timestamp, decodes the exact frame sitting there and writes it as a JPG at near-lossless settings. What was recorded is what lands in the file.
If your frame comes out blurry, that is motion blur recorded in the video itself, not a tool problem. Nudge the timestamp a few tenths of a second either way: action shots usually have a sharper neighbor.