An existing solution would be to use
IMDb2.dll for the episode downloads. It's just a duplicate of the original plugin modified to use it's own configuration. I use it for a different reason, but it's for series and I have disabled images (because I don't want any)—and therefore haven't experienced your 404 issue. BTW, I actually use three copies of IMDb2.dll, to use three different sets of field overwrite settings. The three share the same configuration file, while the original IMDb.dll works fine for movies and people.
...but if it really a problem I can easily separate them.
That might still be a good idea, but maybe it's time to formalize the 'IMDb2.dll hack' so everyone knows it's available as an alternate configuration for whatever reason they may need one. I suspect a number of others are using it, so there's at least a few of us who appreciate it being automatically updated along with the original.
