Where could one publish/post a supplementary video for a published paper?

 It is good practice to share video data or dataset of your research. It could be as a supplementary video or a published peer reviewed video. Some tend to use video hosting sites like Vimeo and Youtube, but the academic community requires Digital Object Identifiers (DOI).

Hence, my submission brought about this question: Where could one publish/post a supplementary video for a published paper?

It should be fine to publish a video, and add the DOI. I believe it is a good idea to publish it.

Videos are among the file types accepted by Figshare, which is an online digital repository operated by Macmillan Publishers. You can create an account for free, and you will get a DOI when uploading files which you can then cite in your paper.

Also have a look at Zenodo, a research data (including movies) and text repository operated by CERN and OpenAIRE. Zenodo will also generate a DOI for your publication, just like Figshare. However, unlike Figshare, Zenodo is not owned by a big corporation.

In general, your video does not necessarily have to be peer reviewed as a supplementary file. But it may have to be published after peer review by a journal, if submitted alongside for a journal paper.

Otherwise, the best place is the one of these repositories or a personal/institutional web page, and give a link to your publication in a video frame itself.

However, I do suggest that you may check out your university's repository. For instance, am in Lancaster University UK, where we use PURE Lancaster, and it accepts submission of datasets, which I assume should also generate DOI - I might be wrong but you can ask the team of your institution, like mine is via library@lancaster.ac.uk or pure@lancaster.ac.uk.

Else, you can use it as a secondary repository as usual, not the primary submission host site for the video.

There are many ones like arXiV to use that will not do peer review of the video publication but your choice is fine. arXiv is an open-access repository of electronic preprints and postprints approved for posting after moderation, but not peer review. It is owned by Cornell University.

You can also use ResearchGate to upload it and generate the DOI.

My advice is to use a repository that will generate DOI for you.

If Mendeley repository will generate DOI, then use it.

The main decision of knowing if it will be peer-reviewed or not should not matter, it is your video.

See the following:

1. FIGSHARE https://help.figshare.com/article/how-to-upload-and-publish-your-data
2. ZENODO https://zenodo.org/
3. arXiv https://arxiv.org/
4. ResearchGate https://explore.researchgate.net/display/support/ResearchGate+DOIs
5. Pure Lancaster https://pure.lancs.ac.uk/workspace.xhtml
6. Mendeley Repository https://data.mendeley.com/

Hope this helps! However, I would like to have more answers and thoughts.