To perform Kasamatsu vaults, the gymnasts do not execute a complete round-off over the table.  Instead, they should repulse the table sideways and continue twisting.  Observe in this slow motion example how the gymnast leaves the table sideways.  By the time he stands up vertically, he is already facing away from the table.  For a regular Kasamatsu, or a Kasamatsu full, this amount of twist will suffice to complete the skill.  At this point, the gymnast should have accomplished at least another quarter twist for a Kasamatsu double-full.  To measure his ability to land the skill safely on a regulation mat, this gymnast is training the Kasamatsu full on a resi mat placed higher than the competition requirements.