Thank you. :)

As for your question, I can answer here: Use of film stills is allowable under "fair use" law (in the US and the UK) in the context of film reviews, commentary, and the like. Hence my inclusion of them. One simply has to credit the appropriate distributor (you are quite right when you say those who credit IMDB or whichever site they got the still from are crediting incorrectly).

One small caveat: It is important to use stills from the films, but not press photographs taken on set or separately, as in such cases one would have to credit the photographer and probably pay for rights (unless the material is used as part of an EPK - Electronic Press Kit - for general media use as part of promotion, normally during the original release, though rights to "fair use" on such items may be restricted to a certain time period). The same applies to film posters (after 1978, for some reason), which I also generally avoid.