intermittently video stops and continues playing

Video tends to pause and re-buffer because the computer can't download video data fast enough to keep things playing.  This could be a connectivity issue between your computer and your cable modem/router/etc, a connectivity issue between your house and your internet service provider, or a connectivity problem between the ISP and the server that's publishing the video you're watching.

The first thing to check is to plug the computer into the cable modem directly with an ethernet cable.  If things are playing fine, then plug it into the wifi router directly.  If things are still playing fine, but they play poorly over wireless, then you know that you need to look at your wireless connectivity situation.  If things play poorly everywhere when plugged directly into the cable modem, do they play poorly on a specific site, or all video sites?  Do they play poorly on other computers when plugged directly into the cable modem?