I have a plugin called jekyll-spaceship in Jekyll - It helps me to use video feature (not available in Markdown): ! [Video] (https:// vimeo. com/633912445?height=500)
If the result of {{ post.content }} is un-rendered raw Markdown, then you could feed it through the markdownify filter. I.e. {{ post.content | markdownify }}.
I am not familiar with that plugin, but you could do this with a little liquid include tag. I know you lose the markdown option, but it might be a better solution for you? Here is a good GitHub resource that will walk you through the easy steps to make it work. No need to download the repo; check out the readme file.
The basic idea is to add a file called vimeo-player.html in the root _includes folder of your Jekyll site (create the folder if necessary).
Then, inside the vimeo-player.html file, you set up the code, like this: