Claudia,
Yes, you can drink green tea, though it's recommended only up to 3 cups of caffeinated beverages a day, since people doing MF are more sensitive to the effects of caffeine.
About the 10 pounds a month "guaranteed" loss though, I am (no offense to you!) pretty darn skeptical.
The caffeine might rev up your metabolism a bit, but I don't think enough to drop that much weight, if no other changes were made to diet or exercise. Although... hey it can't hurt I guess.
Green tea (and black tea) is reputed to have lots of benefits, since it has flavonoids, or antioxidants, that may reduce the risk of several diseases.
Here is an interesting blurb from WebMD, from their "Tearooms Offer A Healthy Buzz" article online:
"Laboratory tests have also shown that black and green tea may help boost metabolism to aid weight loss, block allergic response, slow the growth of tumors, protect bones, fight bad breath, improve skin, protect against Parkinson's disease, even delay the onset of diabetes."
Hmmm! Bottoms up!