Whenever I use a floor corker the way he says to, in one quick push, it ends up launching the cork through the neck and into the wine. I find I have to very carefully ease the handle down. What am I doing wrong?
My guess is that the plunger needs adjustment. That's the metal finger sort of thing that pushes the cork down as you push the handle down. There should be a screw-type limiter that limits the amount of travel (a depth setting, if you will) of the cork. Once properly set, you shouldn't have that issue any more.
You can buy cork capsules - I use the PVC shrinkable ones - from any reputable winemaking supply store. If you don't live near a store, they can be purchased online and, since they weigh next to nothing, shipping should not be that high.