Unknown file type mp4 when importing in Framemaker 2019

I have a number of videos, both MP4 and FLV, that I want to import into a Framemaker 2019 file. Every time, regardless of the selected format, I get an Unknown File Type box that asks me to convert from the format of the file I've selected (e.g., if I import MP4, it asks me to convert from MP4, same with FLV). How do I import without converting? Since Flash player is going EOL, I need to use MP4 so that customers will be able to view these videos in the PDF output without depending on Flash.