This is a radio-show hosted by Masakazu Morita (Ichigo Kurosaki's seiyuu). He interviews other Bleach seiyuus in it. (Too bad it doesn't have subtitles. You can still get a pretty good view of what they're talking about.)
This time the interviewee is Ryotaro Okiayu (Byakuya Kuchiki)... and seriously, I would NEVER have believed Ryotaro to have a girly giggle before hearing THIS! xDDDDDDDDDDDDDDDDDDD ...I can probably never take Saga and Kanon from Saint Seiya, Scar from Fullmetal Alchemist, Dark from DNAngel and Brad Crawford from Weiss Kreuz seriously again... and least of all Byakuya.
Anyway, the extremely high-pitched cackle is Masakazu's. The more reserved, girly one is Ryotaro's.
They both sound so cute when they screw around. And that is what they mainly do. They both joke around and laugh a lot. (Like Ryotaro saying Sanbonzakura instead of Senbonzakura, and in another Masakazu/Ryotaro interview Masakazu is singing about the other seiyuus and making Ryotaro giggle like hell during the "Sugiyama-kun" (aka Uryuu Ishida) 'song'. )