I don't know if there have been any clinical trials on the particular product that Dr. Oz is promoting, but there have been several studies published in peer-reviewed journals on the effects of green tea on metabolism and weight loss.
The 2008 study Green tea extract ingestion, fat oxidation, and glucose tolerance in healthy humans found that "average fat oxidation rates were 17% higher after ingestion of green tea extract than after ingestion of placebo."
In 2009 Green Tea Catechin Consumption Enhances Exercise-Induced Abdominal Fat Loss in Overweight and Obese Adults studied the effects of green tea catechin "on body composition and fat distribution in overweight and obese adults during exercise-induced weight loss." The study found that green tea enhances exercise-induced abdominal fat loss. (Note that the placebo used in this study was caffeine.)
In 2010 Green Tea Supplementation Affects Body Weight, Lipids, and Lipid Peroxidation in Obese Subjects with Metabolic Syndrome showed that green tea caused a significant decrease in body weight, body mass index, and cholesterol levels.
Reference: Does Green Tea Speed Up Your Metabolism?