Youtube videos digitalized for a few seconds, then stuttering

[birdfoot]

Youtube videos watched while on the youtube have been sounding very digitalized at the beginning, then they hiccup through most of the videos but often stop hiccuping at some point through the videos near the end.

The problem doesn't occur with downloaded youtube videos.

Is there a way to fix this?

[birdfoot]

When I say "digitalized", I mean that for a few seconds it sounds like the person talking is a fast-talking synthesized voice.