The video starts out with an academic primer about flow and turbulence.  It then goes on to explain the three different testing methodologies Tunze employs to demonstrate flow quality differences.  Tunze compares multiple Tunze and Ecotech propeller pumps using these methodologies.  The demonstrations show Tunze Streams have more laminar and consistent flow patterns with greater range whereas Ecotech’s Vortech pumps have more turbulence, wider dispersion, and less reach.

For context, please read the Advanced Aquarist article: “Experimental Comparison of Measured Flow Output of Aquarium Propeller Pumps”