What is underneath store shelves

Every week, when we go shopping, we see items on the shelves, not in any other position, just on the shelves. However, there is apparently something below these shelves. Yep, the shelves we walk by every week are hiding something. What could it be? Surely, not too much!

Music used:
Managing Mischief by Bryan Teoh.
Licensed under Creative Commons: By Attribution 3.0 License
Rush by Rafael Krux.
Monsters in Hotel by Rafael Krux.
Magic in the Garden by Rafael Krux.
Licensed under Creative Commons: By Attribution 3.0 License
Wakka Wakka by Bryan Teoh.
Also Sprach Zarathustra, Op. 30 by Richard Strauss; Fritz Reiner; The Chicago Symphony Orchestra.

0:00 Intro
0:38 Produce
4:36 Aisles
11:19 The Final Dump