Video playing only after re-opening project

Hello. I’m a Windows user. When I drag WMV files to the Research folder (MP4 doesn’t work, but I don’t mind converting to WMV) and play it on Scrivener, I can only hear the audio and the background is white. When I close and open the project again, the video plays perfectly UNTIL I type something in the Draft folder and I’m back at hearing only audio and white background.
Also, when I double-click the video index card and select “Open in other editor”, it also works fine.

Why is this and how can I fix it?