In a double, where two constrictions are available, improved cylinder and modified are a good pairing, especially in fixed-choke guns. If screw-in chokes are an option, try a more forgiving match, like skeet and light modified. Shoot the more open barrel first on the covey rise, then the tighter barrel as the birds make their escape.
The CD and DVD have a single track of data in the form of a spiral, which starts as the center going outwards. The data is stored on the bumps or pits which are then read by the CD/DVD layer. The bumps/pits on a DVD are much smaller than on CD, allowing the DVD to store more data.
The limitations are there is less space to store a video on a cd vs a dvd. A cd can hold about 800 meg max, a dvd either 4.7 or 8.5 gig. Yeah. Even though they are the same size, a dvd holds 6 or 12 times more data. This means that you are constrained as to how much and how good the quality of the video will be. A 90 minute movie can be made to fit on a cd but quality might suffer.