squirmy worms! i must say, after having to administer a lot of medication to chinchillas who didn't like to be held or, in mae's case, who tried to bite anything that came near her when i got her (she doesn't do that anymore, she's a sweet sweet girl now), i have worked out just how exactly to hold them.
i find that if i sit on the floor and have them on my lap against my tummy, they feel safe that they're not falling and their back is 'resting' against me. i don't lie them down upside down like the video - that chin is soooo chilled out! - i have them upright, slightly leaning back and hold them firmly around the tummy (careful with the floating ribs!) with one hand and do the check with another hand while sticking my head out so i can see.
i know. not easy.