• Download yt video using youtube-dl preferably
• Go into directory with downloaded file
• Create new directory (it will contain frames)
• Go to newly created directory
• Run command ffmpeg -ss 00:00:08.53 -i ../PS3・PS4・PS\ Vita『STEINS\;GATE\ 0』アマデウス“紅莉栖”-iTmZTOTM8JE.mp4 frame-%d.png -hide_banner
• Put frames from 1 to 67 into contents/splash/images/ (inside splashscreen folder, not included due to copyright)
• Place splashscreen folder in ~/.local/share/plasma/look-and-feel/ (FOLDER HAS TO BE NAMED Amadeus CASE SENSITIVE)
• Activete it in System Settings -> Startup and Shutdown -> Splash screen

WTFPL