Have replaced the DVDArt_Plugin v1.0.2.2 found here, as it was not working properly as reported by fischy667. Please those of you who downloaded it, can you please re-download from same link. Apologies for inconvenience caused.
Encountered the same error as Fischy, now tried to DL from the link above, and browser says that that site has broken contents - not your day, m3rcury
EDIT: DL works now
@catavolt, is this the latest one uploaded 3hrs ago as fischy667 had that same error with the previous release and the latter addressed the issue for him.