It would be better if there was a button or floating button added into the video that is being played, but it works the way it is with hotkeys, thanks for your work!

If you could specify the year, month, day, hour, minute, and second in the save file name, it would have been convenient because you could arrange images created from multiple videos in the order in which they were viewed.

Works like a charm. Easy to use and produce high compression rate files. It would be great if there is also a Chromium version.