Hi, majority of mobs are bugged - despite of successful message "The Spoil condition has been activated." when mob dies it doesn't glow blue ,sweeper cannot sweep anything.
Some mobs work like a charm, some have 50/50 spoil success, and some have less than 10% percent.
Here's a little example which I recorded on youtube - https://www.youtube.com/watch?v=6HXj-bPYpdI
It's not a bug, you were simply unlucky to get any item from spoil list.
Let's take the mob from your recorded video.
On our server here is the spoil list of the mob named: Zombie Captain's Spiritual Body
corpse_make_list={{[tsurugi_blade];1;1;7.5477};{[homunkulus_s_sword_blade];1;1;7.5477};{[rp_samurai_longsword];1;1;2.2593}}
This means without any boosts (Vote Spoil Rune, Christmas Event Carol - Spoil) you have the best chance of 7.5477% getting an item from spoil list.
Statistically you have to kill 100/7.5477=13 mobs with active spoil on it to get either Tsurugi Blade or Homunkulus Sword keymat. All the boosts counted in: 7.5477 x 1.4 = 10.56%, so statistically every 10 mob you surely get a keymat from spoil. Hope you understand the explanation.
Yes, now it makes perfect sense, thank you. :)