I only know about 大型设备 or 大型机械, but I saw a phrase 八集大型纪录片《强军》, but don't understand what 大型 means in this context.
If it means the long hour, it has only 8 episodes, and if it means the big size of screen, it must be played in a movie theater but it is a TV program not a movie production, which is usually played on TV set at home.
Very interesting topic. To my memory, 大型纪录片 is a relatively new word. Before 大型纪录片, Chinese natives are familiar with numerous programmes begin with 大型. Some are shown above, and more examples can be obtained by searching with the keyword 大型综艺.
They are not always so '大型'. But why do they dare call themselves 大型? Well, I would say that's 中国特色.
When 大型纪录片 is used ... what does 大型 refer to?
Sometimes 大型 refers to #3, but most of the time it is for #4.
However, the term 小型纪录片 is usually only used by 纪录片专家 (specialists), and means 小型的纪录片 literally. If a 纪录片 calls itself a 小型纪录片, it is usually REALLY 小 - but still can be longer than some so-called 大型纪录片. For this reason, a 大型纪录片 needn't be longer than a 小型纪录片. Haha!
My understanding is that it means full-length documentary, or featured documentary.
A feature film in English is a movie with the duration of a typical TV program slot, or movie theater slot, i.e. 90 or 120 minutes.
Documentaries (纪录片) are usually short, I guess because of the disproportion between budget and amount of footage required for a 120 mins final cut.
So 大型纪录片 is a "large-scale" documentary with a long duration.
Disclaimer: I'm not confident about this explanation.
Think of it as a documentary version of a blockbuster film or an AAA video game. It does not have a precise definition and is big-scale in more than one aspect.
To name a few:
The previous answers mention the first two factors, but not the rest of them, which are usually entailed in the expression.
If it means the long hour, it has only 8 episodes
《强军》is the title of the documentary series and the eight episodes are its chapters. In other words, 《强军》is an eight hours documentary.
Typically, a documentary refers to one single show. It could be a 30 mins T.V. show or a feature-length movie
《强军》 covered all aspects of China strengthening its military force. With so many contents, that it has to be broken down into eight sections. calling it a 大型 (large scale) 纪录片 is appropriate.
A documentary with 8 episodes is atypically large unless the length of each episode is around 10 - 15 minutes. Thus, the content alone can be huge (內容詳盡且涵盖甚廣), not to mention the filming can be 耗资鉅大, 編, 導, 演, 人員眾多, 場景雄壯 and 聲勢浩大.
