For real. My cat was still tipsy after the castration narcotics and wanted to climb to his favourite spot but couldn't walk straight. I had my hand under his to catch him. He scratched me like hell. Well he didn't hurt himself.

They use their claws to cling onto things. So in panic while trying to cling onto something you can bet that the claws will be out while they frantically (as seen in the video) throw their paws around in hopes of catching a surface.