In 3.7, when one sets up an assignment, there is an option to restrict what file types (docx, pdf, etc) can be uploaded. And there is a global setting ... https://yoursite/admin/settings.php?section=assignsubmission_file
Default accepted file types ... is * ... which means all. To see what that means, click the 'Choose' button next to that setting.
In your case, folks that might respond to this, probably would be more accurate in their response, if they knew what your site is about. To save time ... film.
My 2 cents below ... and the only experience I have had related to digital videos was a State wide contest for K12 students in a Moodle - which involved 'judges' review of videos + feedback for each video - seen only by teacher/sponsor that submitted videos on students behalf ... some students under the age of 13.
Unoconv/LibreOffice route of course won't gen PDF's of videos for annotating. Other option is Google ... and I doubt Google Document converter will do videos to PDF's.
What assignments, which would require a student to upload a file, might be made in a moodle site all about film?
Are there in existence sets of templates for MS Office or LibreOffice related to film industry? Or are there websites that provide live/online interface for the creation of 'documents' used in producing a film? A quick Google search rendered the following link in the top 5 hits:
Have not used above so dunno specifics and if it could be directly interfaced with a Moodle or not.
Not saying only way but for something like a clip of a film, use of a rubric might be in order.
Like I said ... my 2 cents! Hope this gives you something to explore/contemplate ...
Hopefully, there are others who do 'film' / video on Moodles that could share their experiences.
'spirit of sharing', Ken