New media player looks very cool

But there's one thing still bothering me a little...

Why Is it still loading some of the videos so weird? It loads a few seconds, than pauses, loads a few more seconds, repeats...

It struggles to load this one: https://www.newgrounds.com/portal/view/765415

But this one is just smooth: https://www.newgrounds.com/portal/view/758529

This kinda thing never happen on youtube or any other video platform (Its all smooth as butter there (even 4K)), I also tried different wi-fis so thats not the problem...

Is this just a me-problem or...

whw wwhhw hwh?