I think if you check your Steemit blog, you'll find the post of your video and you can edit the description and tags if you want. I was able to edit the tags on one of my videos after it was published.
I wish I could say the same for thumbnails, but I don't see a way to do that yet.
RE: D.Tube 0.4: Serious UI Lifting & IPFS Backup & New Domain & More