Black bugs????

[Hellothere12]

I no they are bad videos but this is what I found on my frags, after picking them up from my friends tank who was watching them for me as my new tank was getting setup. They are around one mm in size(if that) they didn't move like black bugs like I have seen in other videos.(all twitchy) They almost moved around more like a worms. But clearly as you see in my videos they have legs. Any idea?

 

[Clowns-corals-cats]

Aren't they just amphipods or copepods

 

[Hellothere12]

There pretty big is my concern.