Of note is the fact that the three most-viewed videos on the channel capitalize on some popular trends that have been a part of YouTube. The top video (below) was posted back in 2009 and combined two heavily-viewed forms of videos: flash mobs and marriage proposals. It may be not the first proposal they've posted but it was the most successful clip overall with 4 million views.
In addition to posting interesting time-lapse videos (another popular format), DisneyParks has also produced a number of tilt-shift videos like the one below that has nearly a million views. (See: 10 of the Most Popular Tilt-Shift Videos.)
Earlier this Summer, a new video hit YouTube starring a pop-culture icon who has quite a large fan-base on the site. That video already has 1.3 million views thanks in part to the Star Wars crowd.