That's a fairly typical vagrans feeding response. The males are usually a bit more brutal than that and the females a bit less.
By contrast, the tetrataenia I have will usually just gently nip the mouse and let go 3-5 times before it finally holds on. Even then, it's a really weak hold and it will wait up to a minute before it starts swallowing it.
"bing bing bang a bang a bang bing bong bing a bing bang a bong
binga bing a bang a bong bong bing bong bing banga bong"
That yearling eats just like Mama does... She's just slow and dainty when she eats :P She also doesn't strike much, just just packs them down quite a bit.