Anyone know why D.Tube videos display the "loading" spinning circle v's YouTube just playing?

[lexcameron]

Does anyone know why I often encounter D.Tube videos display the "loading" spinning circle thang and a long long wait for a video to play - minutes v's YouTube videos simply playing?
Sometimes D.Tube videos just play.
...but it's all those times the video doesn't that makes D.Tube frustrating/almost impossible.

https://d.tube/