Those cells belong to an aquatic plant called Elodea canadensis, it’s a pretty common waterweed and it can even be an invasive species. In the video you can see the cytoplasmic stream inside the cells of the plant. The small round dots moving around are the chloroplasts! Chloroplasts are small organelles that contain green chlorophyll pigments involved in photosynthesis! These pigments are able to capture energy from sunlight and convert it into energy the algae can use.