is generally the same kind of thing as a "Thesenfilm", but "philosophical" is bandied around so much nowadays I'm sure it's even been used at one time or another to describe the superficial tosh churned out by Richard Curtis and generally starring the dire Hugh "Acting? What's That?" Grant.
(Phew. I feel better now.)

If I had to do this, I think I'd use something like "a (dry) film about philosophy and political theory ..."

I'd steer clear of "dialectically oriented" unless you're a card-carrying Young Hegelian (just saying that makes me feel so clever).

?