I have the type of anchor referenced in this video 4lbs or so. The key is to have the "release" in case it gets stuck.
I don't use an anchor pully BUT do connect the anchor to a bungee cord to the kayak to allow for some relief/give from sudden water movements. Otherwise you could tip the kayak.
I put a float at the end of the line where I tie to the kayak, just in case I quickly needed to release the kayak from the anchor.
http://www.youtube.com/watch?v=-47vOJZe01c
I think I've used the anchor 2x.