I found a way to post on Instagram with subtitles this morning. I think Insta is meant for people to record video on their phone and post it right into the app. I have noticed people like AOC with extensive posts to their "story" that are captioned/subtitled. I think she has some tool, or a staff person who helps her, that enables her to do this very painlessly.
I really prefer my laptop (MacBook Pro) to my phone. Instagram in a desktop browser seems to be very limited though. So I found a python program that is open source that does captioning using OpenAI's Whisper service. https://github.com/m1guelpf/auto-subtitle I am going to see if I can give this guy a tip, this program seems excellent.
I can use photo booth on the Macbook, and this program will caption the .mov file and convert it to .mp4. I think some heavy lifting is being done by the wonderful ffmpeg.
I don't like the idea of Instagram controlling my content. Maybe I'm now an old man yelling "get off my lawn", but I think HTML and files on a web server that I control is a much better way for people to publish. I was jealous of all the insta postings though, which seem to be a way to communicate that is so popular.
When I was helping teach high school kids computer stuff last year, they had no understanding of files and directory structures and so on. With search, automatic location of "recent" documents, default folders for apps, they didn't really need to. Maybe that way of organizing information on a computer will become archaic. IIRC when I had some encounters with mainframes, they required that you specify information about how something is stored on a device, and did not have directories per se. I'm used to thinking I can just locate a file in the directory tree and append to it at will. I learned about files and directories in about 1986 on a PC and a Mac, so that's my perspective. My grandson navigates phones and such very well, and was doing so before he could read. Myself, I find the icon-driven UIs of the current age baffling. Guess I _am_ an old man. Hannah Frankson of Peloton would say "the kids these days, they have no idea!"