A double-feature from the award-winning Nature series. Walking with Giants features Canadian naturalists Charlie Russell and Maureen Enns's remarkable South Kamchatka Sanctuary (including their interactions with three now full-grown orphaned cubs who they fostered) . Showdown at Grizzly River, filmed at McNeil River Falls in Alaska, shows the bears gorging on salmon. 112 minutes. DVD  (SIB46, $19.99)