Identification of small creature
The creatures in the video do indeed show the shape, size, coloration, and typical behavior of ostracods ("seed shrimp"), a type of freshwater crustacean (class Ostracoda) that is distributed worldwide (Martens et al. 2008). They lay eggs either on plants or directly in the water as plankton. Some researchers consider them to be potentially useful as bioindicators (e.g. Ruiz et al 2013), or even keystone species (Lawrence 2002). You can find many photos of ostracods on the Internet.

Lawrence, J. et al. 2002. Microb. Ecol. 44: 199
Ruiz, F. et al. 2013. Int. J. Environ. Sci. Technol. 10: 1115
Martens et al. 2008. Hydrobiologia 95:185