Part of that tension is in your arms and shoulders and it is a result of holding your position and not giving in to the pressure. Besides helping to center your spin, this tension is also where all the power in spinning comes from. Once you give up the tension, the spin is going to fizzle. The other most common reason for traveling is holding the free leg out to the side with an open hip. The free leg is supposed to be held high and in front with a closed hip.
Most skaters leave it hanging out to the side.
This will cause the spin to travel in the opposite direction the leg is hanging. You can very clearly see the high leg in front in all of the clips. Like the shoulders, there should be a tension is your free leg. The tendency is to open the hip to relieve the pressure. This will cause the spin to travel.