I thought the average !programminghumor@lemmy.world user is already FOSSpilled. Of course you don't have to use the FOSS tools but they are convenient enough to be able to make this in 10 minutes.

Anyway, the relevant commands are

yt-dlp -f "bv*[height<=480]+ba" --no-mtime --convert-subs srt --write-sub https://www.youtube.com/watch?v=9SOryJvTAGs
# aegisub needs srt; we don't need above 480p

aegisub "The B-52's - Love Shack (Official Music Video) [9SOryJvTAGs].en.srt"
# now go rewrite appropriate lines in gui, apply style and save as "LoveShack.ass"

ffmpeg -i "The B-52's - Love Shack (Official Music Video) [9SOryJvTAGs].mp4" -filter_complex "[0:v]subtitles=LoveShack.ass[s];[s]crop=w=640[f]" -map [f] -map 0:a -ss 49 -t 21 -acodec aac -vcodec libx265 -crf 20 crowdstrike.mp4
# crf 20 for generously high quality because file size is small anyway

# or for Lemmy upload (no sound, WebM to prevent encoding...
# ...and subsequent ffmpeg timeout errors; my instance limits uploads to 10 MiB)
ffmpeg -i "The B-52's - Love Shack (Official Music Video) [9SOryJvTAGs].mp4" -filter_complex "[0:v]subtitles=LoveShack.ass[s];[s]crop=w=ih/3*4[f]" -map [f] -ss 49.5 -t 21 -vcodec vp9 crowdstrike.webm
# note that Lemmy instances limit videos to 900 frames (usually 30 s) by default

I didn't bother recreating your subtitle and cut timing but I did crop the video to 4:3. The frame rate is doubled and so is the apparent resolution, while the file size is 6x smaller; the Lemmy version is also about 6x smaller but I went for low-bitrate 720p: