Regarding r162276

A work being a "Still Image MAD" (静止画MAD) is not the same as it being "sound-only" (音声のみ).

Still Image MADs use static images as its main visual component (i.e. animated manga cutouts), while sound-only MADs are just audio with a static image overlay.

Still Image MAD:
https://youtu.be/TqeWuKkAU_g
https://www.nicovideo.jp/watch/sm46444490
https://www.nicovideo.jp/watch/sm46439672

Sound-only:
https://nicovideo.jp/watch/nm8957294
https://nicovideo.jp/watch/sm12450575
https://nicovideo.jp/watch/sm13386084

Is there a difference between 静止画MAD and 静止画 then? The latter was already an alias to sound_only so I assumed that they were the same thing. Looking at some results on NND, it seems the two tags are closely related, and synonymous for some videos.

I'll revert the revision now but perhaps someone can explain the relationship between the two tags/ideas. Thank you for noticing.

t174.2: In this case, "静止画" would be the same as "sound only."

I'd consider such videos tagged as "静止画MAD" mislabeled.