Adam Curtis uses footage as actual text (severely edited excerpt):
The Internet… has also produced a revenge of the written word, and of those who believe writing is the senior service of media. […] The left, with its tradition of print journalism, […] could be seen as attempt[ing] to cut visual mass media down to size. […]
The criticisms of Curtis’ use of archival footage and his editing techniques have some of this spirit. At work here is a misunderstanding of what he is doing. Curtis’ films are histories. Almost all serious written histories are led by the use of archival sources. In practice most of these were produced, and are kept, by institutions of various kinds. So the argument that Curtis is “lost in archives” or or “lost in the BBC archives” is a non-criticism…. This is also the technique of many works of oral history. The statement that Bitter Lake is an “emotional history” is therefore in keeping with this tradition. […]
[U]nlike history writing, Curtis’ films have no footnotes and apparatus: but this is true of all factual films. Having more talking head experts would not solve the problem; it would merely introduce multiple arguments from authority.
Cf. the scenario, which I cannot prove actually happened, in which a documentarian can win an award for writing in a film with no voiceover.