The British Film Institute uploaded this video yesterday, filmed around 1916, of a mischievous and apparently domesticated otter. The BFI writes:
This delightful glimpse of an unusually tame otter was captured by American-born filmmaker and entrepreneur Charles Urban, and may have been part of his 'Curious Pals' series of animal films. Having relocated to England, Urban returned to the US in 1916 to help encourage his country's entry into the First World War; he made several films during the visit.
Submitted by Simon!