The script appears to be an automatic updater, presumably to check for new versions of Xvid. It also appears that you uninstalled that program, but the uninstaller failed to remove the entry that attempts to run the now-deleted script.
Because this entry could be in several different locations, the easiest way to find and remove it is to download (free) Autoruns (or run it "live"): https://docs.microsoft.com/en-us/sysinternals/downloads/autoruns
When Autoruns has completed its scan (it will say "Ready" at the bottom left), click the "Logon" tab. Search for "Xvid" in the "Image Path" column. When you find it, UNcheck the box at the left end of the line and close Autoruns. The error message should no longer appear when Windows starts.