So this is a case not of uploading to a server, but simply importing a file to Videopad. What format are these files and what program was used to save them?
Take a minute to share a file or two that does this and someone here will check it out. Just upload the file/s to a free server, such as Google Drive or MS OneDrive, get a shared (public) link, copy the link and paste it here or to me in a Private Message via the mail envelope in the top-right corner of this forum.
Using Google Drive, if necessary change "restricted" to "anyone with link can view."