If you want to tell about the content or the nature of footage of the documentary, use present simple:
The/This documentary shows domestic(the) violence committed against women
Look at the following sentence:
I saw a sponsored program yesterday on tv where the documentary showed serious(the) violence of horrific nature. (It is in the past simple which you have used)
Violence is a countable noun and can not preceeded by an article such as 'the'
Student or Learner