It's one of the older and one of my more favorite Touhou videos. As you may have noticed it's mostly about the fact that Suika doesn't have any boobs. Poor Suika. She's several hundred years old but they're just not there.
Yoko (a.k.a. TTGL's fanservice) decided to remind us that 90% of all Tengen Toppa Gurren Lagann libido originates from her body. Thank you, Gainax... thank you.