--max-quality not very useful if some formats are not desired
The version of mplayer that I'm stuck with is incompatible with some formats, e.g. 34 and 6. I would prefer to eliminate those formats from the candidate list and still use the implied -b instead of limiting the max-quality to 5. I've run out of synonyms for avoid/blacklist/shun/refrain/prevent etc to pick a usable single letter parameter, so it's somewhat awkwardly implemented as an extension to --max-quality instead.