I don't know about the weight loss, but I do know it can be good for digestion and health. You should be using raw (unpasteurized) cider vinegar, the kind you get in healthfood stores with the "mother" (bits of stuff floating) still in it. The mother is the source of the active probiotics. Regular cider vinegar won't do it, or that white stuff from the supermarket that is really only good for cleaning.
You also don't have to take it straight. Add 1 tbsp. to a quart of water along with 8-10 drops of stevia liquid and you have a sort of vinegar-ade. I actually enjoy the taste and drink it instead of plain water.