2 of 4 added 7 characters in body
exiftool -q -r -if '$MIMEType =~ m{^video/} and
                    $ImageHeight < 1080 and
                    print "$Directory/$FileName\0" and 0' . |
  xargs -r0 echo rm -f

Would remove all videos whose Image Height is less that 1080 pixels (if you removed the echo) in the current directory, recursively.