Hello all. I'm kinda new in this aquarium hobby. Recently, i noticed there are worms in my substrate. As of now, I only see 3 different worms but could be more in the middle of the tank. I'm not sure if this is planaria. It doesn't look like it from the countless youtube videos i see. Doesn't look like detritus either. Can someone point me in the right direction to see what they are and if they are beneficial?

Uploaded a video of it here:
https://www.youtube.com/watch?v=7eC_...ature=youtu.be
Thanks!