You use the same link and so I get the same video. Yes he mixes both systems by using gallons for volume, pound foot for torque and kilograms for mass. Metric uses ° Celsius or ° Kelvin for temperature. What is the advantage of using ° Fahrenheit for temperature like it is generally done in America? Scientific formulas are so much simpler if you use the metric system. The strange fact is that officially America is using the metric definitions to derive the inch and pound related values.