I had a hard time viewing the video do to size. I could not find a way to shrink the video to fit the window. Any ways when I drop an item into an assembly I like to drop it close but off to the side of where I will be placing it. That allows me to select faces for the relations. I also like to have "use FlashFit and Use Reduced Steps" selected in the options control box under the "creating relationship command".
Hope it helps