The fringe events are all over the dial today, or what used to be called a dial, and you can find on TV what also can be found on the Internet: table tennis on MSNBC, women’s water polo during the day on NBC, and archery and badminton on NBC Sports Network. But in prime time, in the repackaged NBC showcase, you can get reliably full coverage of the day’s big events, even if you can’t watch during the day: men’s swimming and women’s beach volleyball.