So, maybe I am missing something, but this video https://ecchi.iwara.tv/videos/qvbx6hpxpukpmdnp isn't showing up under videos as shown here https://ecchi.iwara.tv/users/himmelsky/videos
Why is that?
Click See All and go to the second page. It was his very first video, so it is at the bottom.
Already did that, but the one you are talking about is this one https://ecchi.iwara.tv/videos/r1lpswrwslqvkjo but the one I mentioned isn't listed under his videos.
There is something called "unlisted videos" at Iwara. Those are sort of halfway between public and private videos. You can watch an unlisted video without being friend if you know the URL, but it won't show up on the uploader's user page. qvbx6hpxpukpmdnp that you're asking about is most likely an unlisted video. (As a sample, my own video here: https://ecchi.iwara.tv/videos/y6kejt60gh0oqmbj is absolutely for sure an unlisted video, in case you need to test what unlisted videos look like?)
Note 1: A video can be both private and unlisted simultaneously, but that requires more clicks at the upload, so Iwara videos tend to be either unlisted or private.
Note 2: An unlisted video at YouTube will have the text "Unlisted" written below the video player: https://www.youtube.com/watch?v=Vwx58q-pia4 , but unlisted Iwara videos lack that information below the video player.
Note 3: Iwara had a bug for unlisted videos back in 2016-2017. Suppose that someone uploaded videos at Iwara with "MMD test19" and "MMD test21" in the video titles, and you guessed that MMD test20 probably should exist somewhere on the Internet. Then, if you simply googled for MMD test20 then would google lead you right to the Iwara video URL despite it was unlisted. This bug was remedied sometime before 2019, so google won't find unlisted videos anymore just by simple video title guessing.
I did not notice that there were two versions of it. I agree with goishikaigan mademou that it is probably an unlisted video.
I see, at least that clears things up.