has it been that way always or was it working well with good sound and recention before? its hard to tell why you are having this issue as there could be several reasons behind it. it could be for slow internet connection, audio/video card/driver might have something to do with it, etc. also, is it only youtube video that give you trouble ot other tube or video streaming sites get you the same problem. try to watch videos on other sites like myspace, flixya, metacafe, etc and see you can replicate the issue. if all give you same problem, then its either your connection or audio/video issue