As far as I know, there is not a model boat club at Madrid. However, modellers gather Sundays at 10:30 to sail at a pond -actually a set of four connected ponds-, located in a municipal park, in the south of the city. Access is free.
The boat in the video is a sidewheeler, scratch built by my good friend Eduardo Yraola, who is a far more accomplished modeller than I am. She has steam propulsion, and sails at a majestuous pace.