DTube is intimately linked with Steem, and it always posts to your blog. There are a couple ways around this. One is to edit the post with some placeholder text or something. You probably won't get upvotes, and thus not make money on the video.

Another solution is to use a separate account to post the separate videos. Options to do this include signing up with a phone and email you haven't used before, or you can use a service like SteamConnect's account creation tool (you have to pay steem and maybe SP to set it up) or AnonSteem (pay with steem, bitcoin, or litecoin). There are other services, too, but those options are recommended by Steemit.