"But none of those sites have been directly accessed."
No matter. The DNS stats (as the name says) cannot show the domains been accessed or visited, but can show only the domains having been looked up.
DNS is the phone book of the internet (lookups), not the phone lines (calls - accesses). OpenDNS can only see what has been looked up and never what has been accessed or visited.
There's of course a certain relationship between lookups and visits, because every visit of a domain requires a preceding lookup, but this lookup may have occurred much earlier, because it may still be cached locally, and the actual visit may not require a new lookup. And lookups are usually not raised by humans, but by networking applications like browsers, as they think they need to raise a lookup.
"Could they be showing up from ads or popups?"
Yes, they could, or even not. Again, they show up because they have been looked up due to being used by websites for hosting content and for loading content from.
See here as example the impressive number of domains being involved to host content of break.com - you'll find also your media5.break.com subdomain there!
http://www.webpagetest.org/domains.php?test=151125_Y4_SDZ&run=1&cached=0
It is not an easy exercise to exactly find out what specific content is being hosted on what domain. You would have to analyze the code (HTML, CSS, JavaScript, etc.) of the related web page. Don't expect me to do this fruitless time wasting work for you...
