I'm assuming this change will mean that it can use the video thumbnailers already installed rather than specifically needing ffmpegthumbs which would allow more control over the thumbnail generation if someone wanted to modify the relevant thumbnailer file without needing to patch ffmpegthumbs to make the change.

Having said that I wonder, for video files, if the ThumbSequenceCreator functionality will still work in dolphin and show a sequence of thumbnails on hover for videos if it's not using ffmpegthumbs.

Edit: With this in production, I can confirm that the change does enable you to use the system thumbnailers, in particular I now use the system ffmpegthumbnailer instead of ffmpegthumbs. I can also confirm that the ThumbSequenceCreator functionality doesn't work for the video thumbnails when then thumbnails are generated this way.