Hi Kandeycane and welcome! When people talk about what rotation they are on, it means that they are doing a particular weekly workout program that they have themselves put together (based on their goals) or following a workout program that is already designed on a workout video or by a personal trainer.
Remaining on a particular rotation can last anywhere from one week to 12 weeks, even 16 weeks, but most typically people stay with it for about 8 to 12 weeks in length (especially strength training rotations). It is best to switch your rotation when the one you are currently doing does not challenge you nearly as much as it once did.
An example of a rotation would be the Pure Strength Series. This series is a total body strength training program and it is recommended that you do each tape in the series one time per week. Now when you first start the rotation you will notice the most results because it so new to your body. Eventually, your results will slow down as your body gets acclimated to the workout program. At that point you can increase your weights for the exercises to keep the challenge going. At some point though, you will feel that you are either mentally or physically no longer inspired by the results. At that point it would be time to change to a different workout program. Hence, start a new workout rotation.
Hope this helps to explain it a bit.
Enjoy your new videos.
