Just what it says on the tin.
Doing so produces the following error:
https://i.imgur.com/doumsWH.png
Searches suggest this means a version of ffmpeg that won't work in XP is being triggered. These searches say if the newest XP compatible version of ffmpeg is used that this can be avoided, but due to the way VideoPad integrates codecs, there's no obvious way to drop in an ffmpeg file. Seemingly VideoPad includes two different versions of ffmpeg already; this may be a red herring. All I can tell you is it doesn't work.
Reported though bug reports on 8.56
If you have any suggestions, please share them.