BEIJING — Youku, China’s biggest online video firm by revenue, has won approval from shareholders to buy its closest rival Tudou, in a $615 million deal it says will make it the most competitive player in a fast-growing industry.While Youku and Tudou started out copying the business model of the banned YouTube in China, Youku now focusses on providing licensed content, which is good news for Hollywood and other overseas shingles trying to break into China. Youku said the tie-up will cut licensing and network costs, and generate savings of as much as $60 million a year. It will also help the company extend its lead over similar websites run by Baidu and Tencent. Youku shareholders’ passed the all-stock transaction with Tudou in a ballot, the company said in a statement. The decision was ratified at the annual meeting on Monday. Beijing-based Youku has about 21% of the Chinese market, Tudou has 11.5%, according to estimates by Analysys. The combined entity will be named Youku Tudou Inc.