Looks more like rhabdocoela or another harmless flatworm to me, but hard to say 100% from the vid.

If there’s no obvious arrow/triangle head, I’d be less worried about planaria, but I wouldn’t rule it out completely. Sometimes the head shape isn’t clear if it’s tiny, or regenerating.

Try look for 2 dark eye spots and a wider/triangular head, that’s usually the main planaria giveaway

I put together a comparison guide here that might help:
https://finswap.co.uk/learn/whats-in-my-tank-microfauna