MPEG-2 works by compressing in two different ways. Within a frame, it looks at groups of pixels (blocks) and compresses them based on patterns it finds within them. This is kind of similar to how JPEG compression work. the Macroblock quantization level describes how loosely the encoded block can represent the original block. The lower the number, the higher the quality but the more data required to represent the block since less error is accepted when trying to compress.
VBV Buffer Size is the size of the buffer required in order to maintain a constant frame rate. Each frame of video in MPEG-2 requires different amounts of data from other frames. Assuming the stream arrives at a constant data rate, a certain amount of buffer is needed to ensure that data continues to arrive in time to present a frame since the rate of arrival may sometimes be lower than the rate of data being consumed. This value allows the player to judge how much data it needs to buffer in order to avoid running out of information to display to the viewer.
Noise Control is a means of trying to avoid encoding inefficiencies from noise present in the video. MPEG-2 and other predictive encoding schemes rely on the fact that video tends to not change from frame to frame. Noise, however, is random and not able to be predicted. This is a significant problem for high efficiency compression since it can't be predicted. Reducing the noise before encoding results in better compression rates as the video is more predictable, but also results in some loss of detail as it is not possible to distinguish between noise and fine detail in many cases.
Write SDE writes out information about the vertical and horizontal size of the frame.
Intra DC Precision is the number of bits used (thus the accuracy) of the DC coefficients. It also impacts how accurately blocks are quantized. Higher values mean more precision is used, but also that higher data rates are required.
Ignore Frame Interval I'm not 100% sure on for that encoder, but generally it allows the encoder to adjust the keyframe interval as it deems necessary. It may use more or less data as needed, low motion video will likely benefit as the keyframes can be further spread out, however high motion video is more likely to suffer if the interval becomes too long.