He says the film crew shot the footage over seven days at his field sites in the River Moyar in Tamil Nadu, India, during which they were really lucky with capturing otter behaviour. They then had to work hard to keep the video length short for the unforgiving internet audience – I thought the end result was excellent! He uploaded this to Youtube and Vimeo just four days ago.
It is interesting that they call the smooth-coated otters “waterdogs”. That was the recorded name used by peninsular Malays in the 19th century – “Anjing Ayer“. Indeed otters are mustelids, one of the Caniformia, or dog-like carnivorans.