This shouldn't happen. BUT if for any reason you don't see your video on your website, try publishing it again.
This should solve your problem and start playing your video instantly.
However, if your problem persist, contact us here or through the in-app messenger (:
When you grab the embed code script before the video is done transcoding, we'll serve a 404 page for it.
These response may be cached by your browser.
When your video finishes transcoding, the embed code is generated, pushed to our CDN with request to clear cache on our side, but it may be still cached on your browser.
So, your video might be working perfectly well, but your browser is caching the old 404 from before it was done transcoding.
What does this mean?
It's probably better to wait until your video is done transcoding to place the embed code on your site. However, if you need to place it before that, remember to clear your cache afterwards to see the most up to date version of your page and video.