Because we didn't have 7 quadrillion stories about where and when it was found and by whom, and we'd have had Rachel Maddow, the Harpies on "The View", CNN, MSDNC, ABC, CBS, Telemundo all demanding to see the video.
Why do you want to pretend that it would not be over-reported with never ending speculation if it was discovered in the Trump White House? We see a lack of curiosity from leftist reporters in regard to the Braindead Administration... (did I spell Biden wrong again?). If Trump's son Don Jr. left a baggie of snow in the situation room we would not have heard the end of it and we'd have had constant demands for video. Whoopi and friends would be talking about how Trump sniffs sometimes during speeches... Yeah... I'm pretty certain that no cocaine was discovered in the living area of the White House during Trump's term.
Now, if it were discovered in the White House library in the living area of the current Administration we'd have magic travelling baggies of coke finally and "certainly" being "found" somewhere that the video "just couldn't get to it"... How do I know? Because it was reported to be found first in the library in the living area of the White House, wound up in the Situation room for a minute, but finally landed in the lockers just outside the living area and magically no video was ever found and they just couldn't tell who brought it into the most secure building in the United States of America... The magic baggie moved several times during their incurious and overtly defensive reporting.
Leftist newsies ignored it all... at least until they could "definitively" say that it wasn't found where it was originally reported to be found.