Dropbox has been tested and it does work. Yet you event provided any URL to test. Videos that has been Encoded with HEVC/h265 are nowhere supported, not even in your Average Browser. Also the Preview Video on Dropbox is not the Same as the Uploaded file!

Yes the video works but the sound does not (it should be the uploaded version not preview)

Also not sure that you can send links to movies on steam

Try to convert it to h264 avc, use something like Handbrake.

it's already at h.264

I think there might be a thing with the Dropbox player where you need to click the sound icon though I'm not sure

I can't say exactly what the cause is, the source is played along with the video, but there is no audio track. It seems to be a problem with the Chromium browser that uses Garry's mod. Although I have no sound in my normal browser, it may be intentional by Dropbox that removed the adio or intentionally changed so that it does not work in the browser.

So I'm sorry, my hands are tied with this. Unfortunately, I also have enough time to create a cinema service where you can watch from other sites.

Alright thanks for trying I'll just have to stream it