This is 'Everyday Objects From Inside', the latest video from the Macro Room starring a bunch of everyday objects that are almost unrecognizable (okay, you probably still know what most of them are) when viewed in super-macro, which then become very recognizable as the camera zooms out. I felt that, just like hearing a mosquito take a double blast from a bug zapper on a warm summer evening, it was very well executed.
Keep going for the whole video. And yes, just like you I did think the marshmallows was somebody's butt at first.
Thanks to The Pete, who agrees they should definitely do one of these for body parts.