What happens when you replace video #1 with video #2?
Embed code for video #1 takes #video 2. So, the same embed GUID (a random set of identifying characters) holds a different video GUID inside.
On the other hand, your embed code for video #2 now holds video #1.
The embed code installed on your website will display replaced video after all CDN caches would start to work :)
My replace video still shows on the preview page...
A quick explanation for this is:
We have both our embed codes and videos identified by their unique GUIDs. Embed codes are containers for videos. Your video preview inside Vidalytics has a link based on video GUID. So, this will always display the same video, even if it has been replaced.
The replacement feature is meant to work on your own website, but not inside the Vidalytics' pages. Quick preview (and its link) is tied to the video itself. Not to the embed code. This is why you can also see your replaced video on the settings page ;)