* Gemstar International Group Ltd., marketer of the VCR Plus videotape recording technology, named President and Chief Executive Henry Yuen chairman, succeeding Thomas Lau, who remains on the board. Yuen's appointment gives him increased power at the Pasadena-based company, which angered some shareholders when it turned down a $2.8-billion, or $45-a-share, purchase offer by United Video Satellite Group Inc. last year. United Video said Lau supported the offer when it announced the bid, though he never publicly stated his position. Yuen opposed the purchase. Yuen, 49, a co-founder, owns more than 6.5 million shares, or a little more than 12.5% of the company's stock, according to proxy material. Lau, 44, also a co-founder, is the majority owner of Gemstar stock, with almost 24%. Gemstar shares surged $5.25 to close at $63.13 on Nasdaq.