Where I can post a supplementary video for my published paper?
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.
Like Figshare, Zenodo will generate a DOI for your publication.
Unlike Figshare, Zenodo is not owned by a big corporation.