Facebook
Facebook's FAQ on video uploads: https://www.facebook.com/help/166707406722029
Instagram's FAQ on video uploads: https://help.instagram.com/2720958398006062/?helpref=uf_share
Youtube
Youtube's FAQ on video uploads: https://support.google.com/youtube/answer/57407?hl=en&co=GENIE.Platform%3DDesktop&oco=0
TikTok
TikTok's
FAQ on video uploads: https://support.tiktok.com/en/getting-started/creating-your-first-video
Vimeo
Vimeo
FAQ on video uploads: https://vimeo.zendesk.com/hc/en-us/categories/201496018-Uploading-to-Vimeo