O.K. When the stitches are that loose on the bottom,it means the top thread is incredibly loose, or the bottom tension is incredibly tight. The bottom tension can't be that tight, so I don't think you have the machine threaded correctly. Look at this thread for how to thread the machine: CLICK HERE
After looking at your video, the thread guide above the top tension disc assembly is in the wrong place. It needs to be over to the right and down until it is about level with the top of the tension discs. The top thread needs to be firmly seated in between the two upper discs, or you have no top tension.