Capital Cities/ABC Inc. yesterday announced that its recently established Capital Cities Capital unit had made its first investment: A $ 4.75 million stake in YES! Entertainment Corp., a new children’s interactive product company.While the investment does include some cash, the majority will consist of advertising time on the Alphabet Web. Size of the stake was not disclosed. YES plans use the ad time to launch its first line of interactive toys, which features TV Teddy, a bear that interacts with TV and vidcassettes, beginning in late summer. Capital Cities/ABC noted that while the Capital unit’s first investment was to a development-stage company, it would make similar investments in more established industry players. YES will be able to utilize network advertising that would normally have been priced out of reach.