A lot of the ads can't be closed right away -- they have a delay before the "x" or "close" button appears and ads are stacked on each other. Just when you first open, then sometimes one pops up every 5 to 10 minutes but you can close it right away. Annoying, but hey...you get to watch.
Don't try to watch the game on mute and listen to Walters on the radio. Tried it two different games, not LHN obviously, but Walters was generally 1 full play or 2 ahead of the stream. It's a never ending spoiler alert.
Edit: Never picked up a virus from the site.