Movie Gallery Inc. turned in a strong October performance, with its stock closing at $18.19 per share, a 21.2 percent increase for the month. The stock posted gains on the heels of a corporate announcement that same-store sales for its third quarter, ended Oct. 6, were 4.7 percent higher than in the comparable quarter of 2001. The company had previously reported it expected same-store sales to be on a par with last year. Movie Gallery's standings also were boosted by the Forbes annual listing of the 200 best small companies in America, which pegged the video retailer in the No. 50