Anybody know a decent youtube video that shows the details of throwing combinations in boxing. For example, in the basic jab-straight-jab, do you step in with the lead leg, throw a jab, step forward with the power leg, straight and than throw the last jab stationary? Or do you keep moving forward?

I don't really have the expertise in choosing which videos are legit.

I'm being taught how to evade punches just by pivoting on the lead foot. How does that work? When my trainer does it, it looks beautiful. He jabs, pivots on lead foot so hes to the side of you, backpedals and than uses the time it takes for you to get back to position to throw combos all in one motion. He does all that with shuffling footwork that confuses me so I can't follow how he throws the combination.