First let me get the bad news out of the way… there’s no CC option for vimeo. The last update on the forum was from 10 months ago promising something would come up in a year or so.
Ok, so now as I crawl back and beg YouTube for forgiveness, it took me a couple hours to find a way to get CCs up on my YouTube videos now that I’ve already uploaded them.
The How To article from YouTube was of very little help to me except to imply that I might need a SUB, SRT, or SBV file. Or in their words “only supported formats will be displayed properly on the playback page”. What this means, as I found out, is that I can upload whatever file I want and YouTube will just ignore it unless it’s a supported format. I must have uploaded a DOC and DOCX file (after using their Preparing a Transcript File article) 5x before I gave up.
Like most things in technology, my answer was found by letting Google direct me to others that had better answers for me. Someone posted an SRT file that I could download and open with TextEdit. Here’s the video that really helped: HOW TO MAKE SRT FILE AND ADD CAPTION TO YOUTUBE VIDEOS
After doing this for about 2 hours I was having trouble and Googled “youtube cc” and got YouTubeCC which at first glance seems to have been the first solution I should have looked at. Was it on the first YouTube help article? No.