For movie buffs, two new reference works make a strong bid for the bookshelf. In ''5001 Nights at the Movies,'' critic Pauline Kael offers an alphabetical arrangement of capsule reviews written over the years for the ''Goings On About Town'' section of The New Yorker. In contrast to the lengthy appraisals for which she is better known, Kael here artfully compresses the essence of each film (or her view of it) into no more than a few hundred words.
Among Kael's favorites are ''The Godfather,'' ''National Velvet,'' and ''Nashville'' (''the funniest epic vision of America''); she dislikes ''On Golden Pond,'' ''Dr. Zhivago,'' and ''Ordinary People'' (''an academic exercise in catharsis''). Even while disagreeing, inevitably, with some of Kael's opinions, the reader will find them colorful, direct, witty - and never self-important or petty.
''Banned Films'' is billed as ''the first full-length analysis of film-banning in the United States.'' As might be expected from a book written jointly by a law professor and a legal historian, it is authoritative and informative - if somewhat dry.
The opening section chronicles the perpetual tug of war between filmmakers and those who have sought to restrict them - officials, church groups, reformers , or reactionaries - from the earliest silent ''photoplays'' to the present. The second half is a compendium of 122 key cases (such as ''The Birth of a Nation'' and ''I Am Curious (Yellow)''), including a summary of each movie plot, a description of the censorship activity, and an explanation of its legal significance.
Both authors are deeply concerned with civil liberties and the First Amendment. They show that movies have consistently come under attack not just for lewdness, but for any expression of controversial ideas - and that ''the censorial impulse retains its vitality.'' The book avoids prurient interest; I rate the text ''PG'' and the photos ''Approved for All Audiences.''