The reason some files stay longer on Dirty Bin is likely because the person is a Premium Member where their files don't expire. People that are free users that upload their file is removed after 60 days.
The free users links get recycled back into rotation and sometimes a file shows a video has suddenly been replaced by a file other than what they had originally posted. As I check those links if it appears something else is in its spot that looks like it doesn't correspond with the topic at hand, then the link gets marked as removed.
Mab.to links don't keep certain uploaded files on their server that are classified as Adult Content after a period of 48 hours then it's removed as it's not in their policy of storing such material and most goes the same with all Third Party Upload Services.