Cross training means getting is a wide variety of different activities (aka workouts) into your life on a regular basis.
Cross training is NOT doing a workout that is considered "total body" or "functional training." Such as kickboxing, CrossFit, or strength training. Those are just different formats that give your body a total challenge. But, in order to effectively cross train, you'll need a combination of at least 3 or 4 things (I personally do more) on a weekly basis such as: Yoga, strength, pilates, step, kickboxing, hiking, tennis, walking, cycling, playing frisbee, rock climbing, skiing or snowboarding, surfing, playing with your dog… I think you get the idea.
But, the video goes through more detail - through the 5 ways in how it: minimizes your risk of injury, it gives you a better balanced-looking physique, you will look forward to your workouts again, it helps you bust through plateaus, AND it helps you get MORE out of life (while you get fit in the process).