Honestly, although I do agree they have a LOT of unfixed problems and don't seem focused on fixing them, I don't see why any really wants CBR unless they have bandwidth limitations, and since you're not watching it live that shouldn't be an issue. CBR is almost always bit for bit worse. You could come up with a trivial situation where they are equal, but not better. Basically a "video" that is just a still image would compress to the same size and quality. Pretty much everything else is going to have better perceived quality at equivalent sizes. CVBR adds bits as needed to maintain quality and strips them out when not needed. in situations where bits are added, CBR gives bad compression artifacts, in scenes where less bits are needs and CVBR removes them, CBR just wastes bits and gives you better quality. Overall this leads to an inconsistent visual experience, and doesn't save on overall.
The only time I can see wanting CBR is if the CBR version was the master and the CVBR version was re-encoded from it, or if there were scenes that were so complex that the bitrate exceeded your bandwidth for a prolonged period of time, a little bit of this doesn't batter due to buffering.
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As for "800p" and "960p" there is no such beast there are 1080p videos that are actually 800 or 960 pixels high, because of cropping to enhance the widescreen aspect a little. The width is still 1920, they just cropped out the black bands at the top and bottom to optimize filesize.
480p is also know as SD or DVD quality
