Good grief, is she using a big enough nail clipper on that cat? That is suitable for a large dog!
And why is she doing the back claws? That is not necessary.
And she's lucky she doesn't get bitten, holding the cat like that.
My credentials? I trim the claws of seven cats, some of whom are strays I adopted, one of whom was downright feral. If I didn't know what I was doing I'd probably have a lot of scars to show for it!