I do not know of another way to post a video on Steemit, I researched around and found that just copying and embedding a link to you video here is the easiest option.
Now there is a problem with that though, there will not be a thumbnail associated with the video. Unless you drag/copy a photo link and make it the very first image, that would be okay as well.
But for the most part I would want it alittle cleaner, so there is code you can use:
Let me know if there are other options down at the comments section, I would love to know a better way.