I would love to. But not sure how to post to Show HN. I submitted my URL already without "Show HN" on title and it is now lost in the many discussions. Now, I'm unable to submit again.
You still have another chance. I looked at your site and looks like you have an intro video there, but it only shows how to get started with the site, not the background of the site.
Why not create a separate page - "about" maybe - and post a link to it? Be as descriptive as possible about why you created it, how it's useful to people and who you hope will use it to the fullest.
Then, post your link with the title "Show HN: Somevid" or something similar. As long as you have "Show HN" in the front of the title, it will show up in that section of the site.
Remember to be descriptive and try to relate as clearly as possible what you want to accomplish with the site.
BTW, this is Show HN: https://news.ycombinator.com/show . Note, there are guidelines, but as far as I can see your site follows them already so I wouldn't worry too much about them. If you add a new feature, it might help to draw attention to that in the future, but don't create a new "Show HN". On a side note, it may be useful to keep a blog on the side about site news, feature updates etc...
Yes, you cannot post the same URL twice. If you had submitted with Show HN, it should show up in the "new" section. It it gets a lot of upvotes, it'd show up on the frontpage. You might want to delete the earlier post and post it again.