The Ciliated Protozoan
Tetrahymena pyriformis

Tetrahymena pyriformis is a teardrop-shaped, unicellular, ciliated freshwater protozoan about 50 µm long. Tetrahymena species are very common in aquatic habitats and are non-pathogenic, have a short generation time and can be grown to high cell density in inexpensive media:

In the video you can see the organisms swimming, cilia beating and a dividing cell:

Free-Living Freshwater Protozoa: A Color Guide
by David J. Patterson, S. Hedley.
A definitive guide identifying and classifying protozoa as well as introducing collection and examination. This color book makes the identification of individual protozoa easily accessible and provides information on protozoan communities found in different environments by means of a wealth of color photomicrographs supported by original and detailed line drawings and concise text.
(Amazon.co.UK)