How was the file created? What Videopad version is being used? Install this one.
If no success, this may be the fault of the clip itself, despite the fact that viewers may display it.
Convert it with the free Handbrake utility and see if the result loads normally.
If you share a file that has the problem it will be analyzed...
Upload the file/s to a free server, such as Google Drive or MS OneDrive, right-click the link and Share. Copy the result and paste it here or to me in a Private Message via the mail envelope in the top-right corner of this forum. When using Google Drive, if necessary change "restricted" to "anyone with link can view.**