Access to the HD version is a major reason for the uptick.
It's easier to work with in video editing software, widescreen, brighter and sharper, even if flawed from a remastering perspective. The HD is fine if you're going to load it up with filters anyway, though I think some vidders need to turn down their brightness settings for this source (bad idea to use the same settings they use for the dark, grainy, crushed blacks DVD rips).
When people started getting that is when the vids went from one of the absolute slowest-dripping trickles I've seen in years to a sudden burst using both the HD and standard def. sources.