The "(618)" in the filename usually indicates one of two things:
: A non-standard vertical or compressed video height (though 640 or 720 are more common). Common Contexts for this File Girls Forever (618) mp4
If you are looking for a "good piece" in the sense of a : The "(618)" in the filename usually indicates one
: These videos generally focus on high-energy synchronization and "street style" fashion. Girls Forever (618) mp4
: If it is a "618" upload, it often features vibrant urban backgrounds or studio lighting typical of modern dance challenges.