The above definition is partially correct. The thing where you slide on one foot and spell BLOOD with the other is just one move in Blood walking. Crip walking has a similar move except you cross out Blood after you spell it.
Anyway, Blood walking is a style of dance performed by Bloods which is similar to crippin but with no heel toe or shuffle. It sometimes involves spins and shit. Like the Crip walk has a non-gangsta relative called the clown walk, the Blood walk has a non-gangsta relative called the b-bounce. Both are sick.

A casual invitation / threat used by an individual that is not afraid of fucking someone up.

The dance that goes to the Young Bloods song, "Damn"