Suggestion 1: Instead make one snapshot on video, why not make an all thumbnail into one before click on play like vshare or very stream do, at least at my view its way better than a single one... I don't know if its easy or not but it's a feature I would like to see on upstream, every host use a single image it would be nice if the upstream was different from the others in this point.
example:
https://prnt.sc/q4i09c
Suggestion 2: Let us edit embed code, like by default its 640x360 but on my website for example, all embes are 600x600 ive made a small script to only add the url to reduce some time but i still need to catch link by link, if we edit directly on upstream will be way more efficient.
Suggestion 3: Get embed code directly from "my videos" page instead of export or video page.
I know it's a recent service and a lot of effort is being applied to it, I'm just trying to help make it even better and quite different from others. Anyway at least for me upstream is the best option, wonderful and good job...
PS: my problem with change snapshot was solved.