Hey, I am not a regular implementer of @d.tube but one thing I know is they accept virtually all video format and in the process of your uploading the video, they convert it to their own format that is working for their viewers and for you. Just like youtube, they have to compress the file to acceptable sizes that would play on every types of devices. On the android, ios, pc, mac. They use a readily compatible video format for the benefit of the whole populace.
I think uploading .mp4 would be a safe bet and if you've tried multiple different formats it's likely a different issue. I would recommend getting in touch with them via discord or entering an issue in their GitHub repository.
Here's a quick link to join their discord: https://discord.gg/dtube