Twitter? Unavoidable? hahahahaha... ahem. Sorry.
Seriously though, strengthen your will power. Give yourself permission to browse in curiosity on one specific day of the week. If you come across an interesting link or video on any other day, add the link to a bookmarks folder labeled for that week and get back to work. Then, on your preordained Browsing Day, you can open up that folder and explore to your heart's content. Eventually you'll realize that most of the links you've bookmarked are dreadfully uninteresting. You'll begin to hear a tiny, albeit incessant, voice in your head whenever you're about to bookmark something not worth the time to bookmark.