JBJ 8g Nano Reef AIO Rimless Mod/Baffle question

[MarcNem]

Hello All - today, I "accidentally" decided to modify my JBJ 8 gallon Nano Reef AIO tank. What I mean by that is, while picking up the tank, the hood and rim came off. I really only wanted to work on the sump/baffle area to get better filtration. Now that the top and rim are off, I will leave it rimless, but I still don't understand JBJ's sump water flow method. The slits in the baffles don't make sense to me. Any help would be greatly appreciated. I posted a video to help explain a little better. Thanks in advance.

https://youtu.be/y9Op9zbWMU8

 

[MarcNem]

Can anyone with this tank post a pic of the sump?